摘要:

GREAT BRITAIN is an industrial country; iritish Empire, of which it is the ^.centra,^ an Empire of agriculture, and:tt'aordi]4aHly various agriculture conducted " "irdinarily various conditions. At first sight there is little in common between the production of wheat, livestock, or fruit in England and the great Dominions, the growing of rubber in Malaya, of the oil-palm or ground-nut in India and West Africa, and of the sugar-cane or banana in the West Indies. But in truth all crop- or fruitgrowing and all livestock husbandry rest on the same fundamental principles, though their application may present a very different problem in different countries; and therefore all agriculture has at least one common interest-the elucidation of those principles.The Imperial Agricultural Research Conference, which is to meet in London at the beginning of October, will be primarily an attempt to survey and organise the scientific resources of the Empire for the increase of agricultural knowledge. Research has two main requirements-first (a long way first), trained men; and second, equipment. In both these requirements the Empire is, broadly speaking, far below the needs of the work to be done and the problems demanding a solution- problems not of purely scientific interest but of immediate importance for the prosperity, and almost for the existence, of large populations. In Great Britain it is true that we possess, thanks mainly to Sir Daniel Hall, a coherent organisation of agricultural research institutes, reasonably staffed and equipped. But outside Great Britain, and with a few exceptions, such as the Animal Diseases Station which Sir A. Theiler has established in South Africa, agricultural research, where it exists at all in any sense worthy of the name, is sporadic, ill-equipped, and un-organised. Yet in the tropical and sub-tropical colonies alone (without including the Dominions and India) there are something more than 2,000,000 square miles, and 50,000,000 people practically all dependent on agriculture of one kind or another. No conference can provide men or money. Money, however, is now available to some extent from the Empire Marketing Board, which is devoting to the encouragement of agricultural research a not insignificant proportion of its income; the provision of trained men is a matter of time, the offer of a career, and personal inspiration. But the conference which meets in October can and will attempt to answer the question, "How can the different parts of the Empire best help one another in their common aim, the advancement of agricultural science?To those familiar with any kind of research, this general heading willsuggest many specific problems. First and most important of all, there is the recruitment and training of research workers. It is well known that while in some branches of science there is a fair supply of young men coming forward to take up research, in others there is a lamentable deficiency; for example, from almost every part of the Empire there is a demand for trained geneticists, which is, and for the moment must remain, unsatisfied. For the solution of this problem we must look mainly to the universities of the Empire, and particularly of Great Britain. Again, what can be done to help the man now engaged in research? Is the time yet ripe for an extension of the principle already embodied in the highly successful Imperial Bureaux of Entomology and Mycology? For the establishment, for example, of Imperial bureaux of soil science, veterinary science, or agricultural economics? If so, on what plan should such new organisations be set up? Then there is the difficult problem of publications, and of the collection and interchange of information, so that a man examining an agricultural question on the Gold Coast, for example, may have at least a reasonable chance of starting with a knowledge of the work already done or being done in other parts of the Empire upon the same or connected problems. The interchange of research workers is another matter to which a close analysis ought to be applied; if a definite and practicable scheme can be devised, there can be no doubt of its advantages. A man working alone or almost alone in a comparatively small tropical colony, far from the stimulus of companionship with his scientific fellows, must benefit enormously by a period of re-freshmcnt (in the most literal sense of the word) at Cambridge, Rothamsted, or some similar centre; just as those who are fortunate enough normally to work in such centres may well obtain unexpected advantages from a complete if temporary change of surroundings, and the opportunity of applying the test of new conditions to hypotheses and results reached in laboratories and on land thousands of miles away. Another question of magnitude which can only be fully considered at a conference where the whole Empire is represented is the project of an Imperial chain of research stations-how many there ought to be, where situated, and how far each should endeavour to become the recognised authority for the whole Empire in one branch of agricultural science, besides meeting the imperative requirements of its own locality.The conference must primarily apply itself to such administrative or semi-administrative questions; but naturally the groups of specialists present will discuss among themselves their own technical problems, which are scarcely suitable for the whole conference. Possibly, however, the most valuable part of such a conference is not to be found in the official discussions of questions formally brought before the conference or committees of the conference; it is to be found in those private and unrestrained conversations in which one man of science really speaks to another with freedom about his own difficulties, hopes, methods, and ideas. The first Imperial Agricultural Research Conference is sure to be interesting, and it ought to produce most important results in the improvement of the machinery for the supply, equipment, and co-operation of men engaged in research. But one result should follow, which by itself will fully justify the conference; a mutual knowledge and personal appreciation between men scattered all over the British Empire, which will render their co-operation not only easier and more pleasant, but also more fruitful, than it can be made by any official machinery.

ISSN:0028-0836    

DOI:10.1038/120393a0

出版商:Nature Publishing Group    

年代:1927

数据来源: Nature

摘要:

THE preseiil^generatiori regards with relatively. -L smalUfVnarm the probings of a paternal jt into the life and death of the individual. Than a hundred years ago the principle of e was still dominant and the jurisdiction of Whitehall was strictly limited. No longer ago than 1753, a Bill introduced into the House of Commons to provide for a census of the people met with vehement opposition. One member " feared lest some public misfortune or an epidemical distemper should follow the numbering," while another was overpowered by the discovery that there could be " any set of men, or indeed any individual of the human species, so presumptuous and so abandoned as to make the proposal we have just heard. I hold this project," he stated, " to be utterly subversive of the last remains of English liberty." Yet Great Britain did not lag behind other European States. The history of vital statistics is thus a short one, and, consequently, to glean further information of the populations of the past, we are compelled to resort to statistical assumptions based upon the very meagre data that exist. It is this ignorance of the course of population growth, of the variation in birth- and death-rates, over any but a very short period of time, and that limited mainly to a century of rapid industrial expansion, that makes the study of the ' laws of growth ' so fascinating. Few workers have brought more originality to the study than Prof. Raymond Pearl. Approaching the problem first from the mathematical viewpoint (in conjunction with Prof. Lowell Reed), he concluded that a first approximation to the law was to be found in an equation of the form^ea1x+a.zx'' + a,x' + . .. .+auz>' So long ago as 1838, Verhulst, a Belgian mathematician, had used this same curve, which he called the ' logistic curve,' as an expression of the law of population growth. This was unknown to Pear]and Reed when working oil the problem, and they reached the result independently from biological reasoning. Eliminating mathematical symbols, Pearl states his ' law ' as follows: " Growth occurs in cycles. Within one and the same cycle, and in a spatially limited area or universe, growth in the first half of the cycle starts slowly but the absolute increment per unit of time increases steadily until the mid-point of the cycle is reached. After that point the increment per unit of time becomes steadily smaller until the end of the cycle. In a spatially limited universe the amount of increase which occurs in any particular unit of time, at any point of the single cycle of growth, is proportional to two things, namely: (a) the absolute size already attained at the beginning of the unit interval under consideration, and (b) the amount still unused or unexpended in the given universe (or area) of actual and potential resources for the support of growth."Prof. Pearl shows that such a curve gives a good representation not only of the growth in body - weight of the rat and of the pumpkin, but also of the development of a population of yeast cells and populations of the fruit fly (Droso-phila) kept under exact experimental conditions. Applying the equation to human populations, it is found that the curve fits the recorded enumerations with extreme accuracy. Unfortunately, in all cases the observed population-counts cover only a small part of the whole range of one cycle of growth. In the United States and in England and Wales it is the earlier part of the cycle for which observations exist. In France it is the late part of the cycle. What we require is a human population having census records covering an entire cycle of growth. This Pearl endeavours to supply by an analysis of the growth of the native population of Algeria, " the first and only example I have so far discovered of a human population virtually completing an entire single cycle of growth according to the logistic curve, and at the same time having definite census records covering practically the whole of the cycle." The ' fit ' of the curve to the observed enumerations is again a good one. At the same time, we must not surrender ourselves entirely because of this ' goodness of fit ' between the observed and the mathematically expected. Another curve of a flexible type may possibly fit the very limited observations equally well; but one has yet to be discovered based upon equally logical-and justifiable reasoning. In adopting any ' law of population growth ' it is essential to remember that it can be utilised for the estimation of past and future populations only over very short ranges of time. As Pearl points out, any alteration in the resources necessary for growth may entirely change the cycle along which a population is travelling. It was this change of resources that falsified (for the time being) the contentions of Malthus. He was unable to foresee the development of world-wide markets and the vast increase of food supplies, and thus the postponement of the pressure of population upon subsistence.Pearl's experimental work is invariably stimulating, and his later chapters on density and population growth quicken one's interest. His data on normal sex behaviour cannot command the same respect. It is impossible to rid oneself of the conviction that no real assessment of the accuracy of the data is possible, and that a group of men aged from 50 to 75 years, even if of more than average intelligence, would not remember their average sexual activity per month in the different decades of life from puberty onwards. Even if the data presented are substantially correct, the ' exposure to risk ' incurred in all the social classes in this study is so great that one can scarcely credit the variation in sex habit as an important factor of the differential birth-rate. The same question confronts one in a lesser degree in reading Pearl's work on alcohol and theduration of life. Can one ever obtain trustworthy knowledge of the drinking habits of the individual? Pearl is satisfied that the information presented by him at least " is more accurate and comprehensive than any elsewhere available," and states that every critical safeguard of the accuracy of the records was adopted. He admits that it is by no means an easy matter to determine the precise effect of alcohol apart from other factors, and endeavours to eliminate the possible selective factor that determines whether a man is an abstainer or moderate drinker. For this purpose he compares pairs of brothers, one an abstainer and the other a moderate drinker. The moderate drinkers, he finds, are slightly the better lives. This is the same conclusion as that reached in the main study, that the moderate drinkers are as good lives as the abstainers, or even slightly better lives, while heavy drinkers are seriously penalised for their excesses as regards duration of life.The study (and again more especially on its experimental side, of which a very detailed account is given) is full of interest and has been carried out with much care and labour. But it is not possible to feel satisfied that the selective factor has yet been proved to be non-existent, or that the last word has yet been said as to the effect of alcohol upon longevity-a dictum to which Prof. Pearl would be the first to subscribe.

ISSN:0028-0836    

DOI:10.1038/120394a0

出版商:Nature Publishing Group    

年代:1927

数据来源: Nature

摘要:

WHEN a magnificent feast is given and the numerrwISr"dishes are all excellent, it is perhaps una^ftcious to complain that the disorder of the tfwlnrejes makes digestion somewhat difficult, and that the table decorations (the appendices), tlflj^Vrgh interesting in themselves, have not been arranged so as to decorate the table. Yet the excellence of his material provokes this complaint against the arrangement of Capt. Rattray's book. It is somewhat disconcerting to find the ideas of the soul, disease, and medicine all discussed under " funeral rites." So far as practical field method goes we would not change this at all; Capt. Rattray has derived all his knowledge from the sound method of watching ceremonies and discussing them with well-chosen informants, but it would have helped us to understand better had the ideas of the soul been given earlier, and not as an interruption to a ritual which had already begun. For an appreciation of Ashanti social, economic, and political organisation (as for most other ' so-called ' savage societies) this knowledge of the spiritual background of life is essential, because religious ideas permeate everyday life and there is no trace of the division into civil and religious life that we are accustomed to in Europe. For example, law is founded on religious sanctions, just as the curious treatment of a new-born infant depends on the beliefs concerning the soul and the ever-powerful influence of the dead. It would seem that the one desire of the Ashanti is fertility, fertility of mankind and the fertility of the land, and for this end he must keep on good terms with the supernatural powers who are able to bless or blast the life source at every turn. No price, including human sacrifice, is too high to pay for the blessing, but for the Ashanti life is hard because of the multiplicity of supernatural powers. Capt. Rattray has defined these, riot from any a priori conceptions of gods, demons or spirits, animism or mana, but from observation of ritual and the part the supernatural plays in the, life of the individual. Thus there are the gods (abosom), including a High God in the sky, several gods, his children, all connected with water, an earth goddess, and possibly many others, the ancestral spirits (samanfo), and a vast class recognised by the Ashanti as nwnrum, to which Capt. Rattray reluctantly gives the name fetish. If he could, he would abolish that word entirely; instead, he has striven to correct the absurdly erroneous ideas of fetishism that have done so much to vitiate all works on West Africa. Some of the suman are extremely powerful, and it may be difficult for the observer to differentiate between their cult and those of gods, whereas other Kwina/n appear to be specially endowed amulets or talismans.This, however, docs not exhaust the catalogue of supernatural powers; there are forest spirits (fairies), monsters and witches, and animals and plants may have souls, which may influence the life of man. The description of a funeral service held over a dead elephant is very interesting, as the attitude here shown towards animals raises points in connexion with totem ism. The usual socio-religious complex known as totemism does not exist in Ashanti, but there arc certain animals and plants connected with the ntoro divisions (not clan divisions); lists of these ntoro animals and of animals possessing souls for whom funerals are necessary are not identical, though there are a few species common to both. Capt. Rattray does not appear to have followed up this possible connexion, and it is quite probable that it would not lead to any conclusions, but it is a nice indication of the mental attitude towards animals which makes totemism possible. The king of Ashanti does not appear to be a divine king; rather does the divinity of the authority rest in the king's stool or throne. Much insight into the Ashanti religion and its relation to the kingship may be gained from the description of the Odwira ceremony, previously known as the Yam custom, and famous for the amount of intoxicating liquor drunk and of human blood spilt. These two features, though so horribly prominent to the first European observers, are merely incidents to the Ashanti in what was really an annual purification ceremony for the king and the whole natiqn before the new harvest might be eaten. The king honours the ancestral spirits, and the chiefs and people pay allegiance to the king. The gods, ghosts, and other spirits must eat, then the king, his chiefs, and people may do so. This ceremony, which lasted many days, must have been of great political and economic value to the kingdom. It seems a pity, however, to call it a " rite de passage," a title which so aptly classifies those ceremonies connected with transition periods in the life of the individual which mark the various phases of personal development, although M. Van Gennep himself, who coined the phrase, did include certain seasonal festivals under this heading.The cult of the dead kings of the Ashanti suggests interesting politico-economic questions, for in addition to the extremely complicated beliefs concerning the soul, or rather the various souls that go to the spirit world (in the case of the king accompanied by widows and other attendants who are killed for that purpose), there is also a cult of the royal skeletons, to each of whom is appointed a living wife. Moreover, vast treasury in gold was owned by the dead kings and guarded by a standing army of about one thousand men. This money- for gold dust has its standard weights and values in Ashanti-could be ' borrowed ' by the reigning king for ceremonies or national emergencies. The fact that the king must borrow arid not merely take the royal treasure may have given stability to the government and added to the credit of the country. It is to be hoped that Capt. Rattray may still be able to obtain further information concerning this primitive gold reserve. Was tribute paid to the dead and not to the living monarch, or was it divided between them? In what manner did the king make repayments to the coffers of the dead, and at what periods? Were the natural sources of gold controlled in any way, or might any man wash for alluvial gold? Numerous examples are given of fines which must be paid in expiation for breaking taboos or in the more ordinary course of justice, but it is not always clear if these were due to the king, clan chief, gods, or as compensation to the injured party. One notable example of direct taxation, however, is that half the bride-price of daughters of the royal house, as well as of granddaughters and great - granddaughters of chiefs, passes to the king.Apart from the practical functioning of the gold reserve, there is an interesting question regarding its underlying purpose and possible origin, on which it may still be possible to throw light. Capt. Rattray has told us that when a commoner is buried, his wife provides some gold dust, or a small nugget, which is tied in the loin-cloth of the deceased. It is called kra sika, ' soul's money,' and is intended for the purchase of necessaries in the world of ghosts. Is it possible that the treasury of the kings originally served the same purpose, or that even quite recently, while fulfilling an entirely different function, the same belief was held with regard to it? It is to be hoped that in the forthcoming volume which Capt. Rattray promises us, he may be able to tell us still more about the economic side of this highly organised barbaric kingdom. All who have enjoyed Capt. Rattray's first work on Ashanti will appreciate this, his second volume, and will look forward eagerly to the publication of the third.

ISSN:0028-0836    

DOI:10.1038/120396a0

出版商:Nature Publishing Group    

年代:1927

数据来源: Nature

摘要:

IN Great Britain it seems as if almost every na^tajjttfover who can wield a pen writes, or tries^to^write, a work on British birds. In China t^evreverse is the case, and since 1877, when David and Oustalet brought out their " Birds of China," no one has attempted to compile another such publication. Latouche is now engaged on " Birds of Eastern China," and both he and Lord Rothschild have written several valuable articles in the Ibis on the birds of Yunnan, whilst desultory articles on the avifauna of other portions of the great Chinese Empire have appeared from time to time in the same and in other journals. Messrs. N. Gist Gee and his collaborators are now bringing out a tentative list of the birds of the whole Chinese Empire, and we congratulate them very heartily on this part, the first, which has appeared in the Bulletin of the Peking Society of Natural History. The work is one which is very badly wanted, for however good David and Oustalet's work was when written, it is now long out-of-date, and a vast amount of ornithological work has been done since that time. The tentative list will, as its name implies, include all those birds which occur in the eighteen provinces of China, its islands, and in eastern Mongolia, east to Sakhalin. The classification adopted is that of Knowlton in his " Birds of the World," and the nomenclature is taken from Hartert, " Die Vogel Palaarctischen," and other modern authors. No suggestion is made that the list is in any way complete but, such as it is, it is published as a working basis for further study and, in this respect, it is almost impossible to over-estimate its value to both present arid future workers. The list contains the scientific, English and, wherever possible, the Chinese name of each bird, after which its distribution is given. The author of each scientific name is given, but no reference is made cither to the first description or to later synonymy, an omission to be regretted, though the inclusion of these details would doubtless have at once overburdened the work and rendered it impossible to carry out.It is out of place in reviewing a work of this nature to criticise minor details, and it may suffice to say here that as a whole the compilation appears to be excellent and thorough, and the fact that mistakes in nomenclatures and a few inaccuracies in geographical ranges naturally find their way into its pages will not in any way affect its immense usefulness and its great influence in furthering the cause of Chinese ornithology. It is a praiseworthy and very ambitious attempt to fill a greatly felt want, and one which we hope will probably inaugurate another cycle of ornithological research in China. The present volume contains the Colymbiformes, storks, herons, ducks, Accipitres, game birds, rails, waders, gulls, pigeons, and scansorial birds, leaving the great order of Passeres still to be dealt with.

ISSN:0028-0836    

DOI:10.1038/120397a0

出版商:Nature Publishing Group    

年代:1927

数据来源: Nature

摘要:

(1) T 11 HE German Jtfraiislation of a treatise on .!_o comparative anatomy by four Dutch zoologists is. sf welcome summary of the present state ofoMfcTOebrate anatomy, which deals with vertcbrajtes in the same way as, but more fullj tlmnjlGegcnbaur and Biitschli have dealt with the ammsy kingdom as a whole. Some of the illustrations are borrowed from Butschli's text-book, the merits of which have already been described in NATTJRE; and the rest of the 987 figures are drawn in the same clear semi-diagrammatic way. The volume is probably the best text-book of comparative anatomy. The chapter on the skeleton (by Prof. Versluys, of Vienna), dealing as it does not only with recent but also with fossil vertebrates, is worthy of special note for its excellence and comprehensiveness. (2) The fact that Hyman's " Elementary Zoology " is the second edition of a practical manual of which seven impressions have been sold in six years leaves no doubt as to its usefulness in the University of Chicago. It deals in a comprehensive way with the technique of the practical examination of the ana tomy, embryology, and cytology of a large series of invertebrates and vertebrates. It has no illustrations.(3) and (4) The guides to the dissection of the dogfish and Necturus are simple, clearly written dissecting manuals for elementary class work. They are both well done, but have no illustrations. (5) Howell's work on the wood rat is an original memoir on the anatomy of a common American mammal. The author points out that while there are excellent accounts of the anatomy of such spectacular curiosities as the aye-aye and the marsupial mole, we are woefully ignorant of many of the common mammals. His book is one of a series that is being issued by the American Society of Mammalogists to make good this defect. The work provokes comparison with the investigations of the tree shrew and the tarsier respectively by Profs. Le Gros Clark and Woollard, recently pub lished by the Zoological Society of London; andsuch a comparison reveals the curious fact thatthe American author has wholly neglected the central nervous system, to which the British anatomists devote particular attention.(6) Toldt's well-known atlas of topographical anatomy is perhaps the most comprehensive of the many atlases now available for students, and as such is well worth making accessible in this second edition for English-speaking readers. While most of the illustrations are excellent, a few of the wood blocks seem to be worn out so that the detail is lost in the impressions made from them. Dr. Eden Paul's contribution to the volume is not alto gether relevant: his reliance upon Macalister's text-book, which was an excellent guide more than thirty years ago, is not an adequate basis for the explanation of a modern atlas.

ISSN:0028-0836    

DOI:10.1038/120398a0

出版商:Nature Publishing Group    

年代:1927

数据来源: Nature

摘要:

TN organic^hfljKical industry there are many signs -*- -f witter and increasing activity. Synthetic re leading to new supplies of solvents and other products, and in addition the possibilities of wood as a chemical raw material are being realised. Within the last decade artificial silk from wood has become abundant and cheap, and is now being used to an extent never approached by the limited and costly natural silk. The saccharification of wood and cellulose has recently become prominent as a possible cheap source of power alcohol, acetone, glycerine, and other products of fermentation, and although not without technical difficulties, promises to open the way to new industries. In addition to these prospects there is every likelihood that wood cellulose will be pressed into use as a substitute for the more costly cotton cellulose in many existing industries such as film, celluloid, explosives and enamels. Wood, unlike coal and oil, requires only land and the sun for its continuous supply. Fortunately, reafforestation is receiving active attention in Great Britain, as in the main timber-producing countries, and there is no doubt that many requirements can be assured with practically small land reservations. The chemistry of wood and wood cellulose is consequently of increasing importance. Considerable attention appears to have been directed to the subject by the study of wood as a source of explosives during the War.Wood and its products are, however, complex and varied, and a systematic conception of their chemical and physico-chemical behaviour has been wanting. Dr. Schorger, Director of Chemical Research, C. F. Burgess Laboratories, has carried through successfully the difficult task of collecting the scientific data available on the chemistry of wood in a concise account, necessarily including some mention of cotton cellulose and its modified forms. It is made clear in the preface that the technical side of the subject is not the main theme, but the research student and worker will find the literature effectively summarised, while new prospects of research are to be found on almost every page of the book. Broadly, the subject matter covers wood and the reactions of wood, lignin, hemicelluloses, gelatinised cellulose, oxy- and hydrocelluloses, the saccharification, distillation, and digestion of wood and wood celluloses, and analytical methods, concluding with a useful author and subject index. The many problems of chemical constitution, together with modern views on gelatinisation and other physical phenomena, are fully considered, while manufacturing processes concerned with wood and wood cellulose are adequately, although more generally, described.In such a summary it is inevitable that occasional erroneous results can be fovmd and additions suggested. Thus, Jentgen's statement that dry cellulose will take up 3 per cent, of moisture from all known drying agents is obviously incorrect and should be omitted. The following corrections might also be made: on p. 536 aniline hydrochloride to aniline acetete; on p. 578, under copper number, 451 to 541; and on p. 184, Irvine's formula for cellulose is incorrectly reproduced. The paper, printing, and binding are excellent, and the work is to be recommended as the most satisfactory survey of the subject in a convenient handbook form.

ISSN:0028-0836    

DOI:10.1038/120399a0

出版商:Nature Publishing Group    

年代:1927

数据来源: Nature

摘要:

THERE are mansjpncyclopajdic text-books of metallurgy, andS™* new one must justify itself by fullness^ Mia accuracy of treatment. The present vnhijmfe are the work of a large number of con-tr|frraiors, and there is no attempt to give a critical survsy of the subject. Instead, there is a series of monographs on the metals, most space being given to those which are of the greatest industrial importance. Each monograph is by a specialist, so that the information may be supposed to be abreast of modern practice. This appears to be true of the common metals, and such important processes as the electrolytic extraction of zinc arc treated in detail. The term metallurgy has been interpreted by most of the writers as referring mainly to the extraction of the metals, and only in a few instances is there more than a brief outline of mechanical or thermal treatment or of the preparation of alloys. Such general processes as crushing, ore concentration, roasting, sintering, and electric smelting are considered in separate articles as well as incidentally under the heads of the several metals. An extensive and useful section deals with the materials of metallurgical construction. Metallography only receives limited attention, and the brief article on the subject is mainly confined to phase-rule questions, but a few of the authors give some account of the metallography of their special section. Throughout the greater part of the book theory is subordinated to practice, and it is mainly as a guide to current ore-dressing and smelting practice that it will be found useful. The least satisfactory section is that which deals1 with the rarer metals, in which there is now a great metallurgical interest

ISSN:0028-0836    

DOI:10.1038/120400b0

出版商:Nature Publishing Group    

年代:1927

数据来源: Nature

摘要:

IN this book/iTter^'Bergman describes several journeys which/The and his wife took a few years ago in tfig^rinterior of Kamchatka, when he was leadeiwa biological and ethnographical "expedi-tMnf sent by the Swedish Geographical Society. It is the best kind of travel book, with no tedious details of daily routine, but enough incidents of travel to illustrate the customs and habits of the people and the difficulties of the road. There is also much original matter in the account of visits paid to the Lamuts and Koryaks in the remoter parts of the peninsula, and to the- degenerate and disappearing Kamchadals. The book is useful as giving a full and readable account of a part of Asia which is little known and seldom visited except by trappers and fur dealers. The maps and illustrations add to its value. Fuller accounts of the results of the expedition are now being published in Swedish scientific journals.

ISSN:0028-0836    

DOI:10.1038/120401c0

出版商:Nature Publishing Group    

年代:1927

数据来源: Nature

摘要:

ONE of the outstanding problems of radioactivity is the exact relation of the actinium to the thorium and uranium-radium disintegration series. That the actinium series starts at uranium I or an isotope of uranium, includes uranium-Yand ends at an isotope of lead after five α-particles have been expelled between protoactinium and the end product is regarded as proved by the experimental evidence. But the atomic weights of members of the series are not known; protoactinium is the only member of the series whose atomic weight might be determined by the usual methods, but this constant is still lacking owing to the very great difficulty of making a complete separation of protoactinium from its homologue tantalum. An investigation with the mass-spectrograph of uranium or of uranium-load, loading to the discovery of isotopes not ascribable to the uranium-radium series, might also throw light on the atomic weights of members of the actinium series. This has yet to be made.Failing experimental evidence, it may be asked if any useful purpose is served by attempts to predict what these atomic weights may be. As they lead not only to new values-of these atomic weights but also to a generalisation with respect to the stability of radioactive isotopes which in part is applicable to isotopes of inactive elements, as I hope to show they do, 1 think they are justified. 1 assume (a) that the actinium series starts from an isotope of uranium, ends at an isotope of lead, and includes tho product uranium- Y, for all of which the experimental evidence is very strong; (6) that if an element of even atomic number has isotopes of odd atomic mass, these are likely to be one and three units less than the mass of its most stable isotope; (c) that the most stable mass of an element of odd atomic number is likely to be one unit greater than that of the most stable mass (of even number) of the element next 'below it. .(In (fe) and (c) I am. merely applying to elements in the range of atomic numbers 82-92 what is obvious from F. W. Aston's results on elements in the range 34-80.)Now the, most stable isotopes of elements 92, 90, 88, 82, and 80 are known to have masses 238, 232, 226, 208, and 202 respectively. Therefore according to (c) the most stable isotopes of elements 93, 91, 89, 83, and 81 are likely to have masses of 239, 233, 227, 209, and 203 respectively. (This is certain for element 83 and 'very probable for element 81.) Can proto-actiuium have the atomic mass 233 assigned to tho principal isotope of element 91 '/ Now, so far as has been investigated, tho most stable isotopes of elements 92, 90, 88, 86, 84, 83, 82, and 81 are either ' o-rayers ' of long life or products which may be described as potentially ' a-rayers' (bismuth 209 being regarded as the parent of thallium's isotope 205, lead's isotope 208, the parent of mercury's isotope 204, etc.). Protoactinium, an ' et-rayer' with an estimated period of 10,000 years, is clearly in this class; actinium, a ' /3-rayer' with a period of 20 years, is clearly not. The former may therefore have an atomic mass of 233, the latter may not have an atomic mass of 227; and these two statements are consistent with one another, since the former element is the parent of the latter by an a-particlo change. An alternative value for the atomic mass of protoactinium would be 235, since, as F. W. Aston's results show, an element of odd atomic number may have a second isotope two units greater in mass than that of tho principal isotope. The value 233, however, leads to a value of 237 for the mass of that uranium isotope which is the head of the actinium series, a value consistent with assumption (b), whereas the value 235 leads to a value 239, which is not. Again, as the mass 227 may not be assigned to actinium, the mass 231 may not be assigned to protoactinium. If, therefore, the atomic mass of protoautinium is an odd number, that mass must be 233 if the assumptions I am making are valid. This value fixes the atomic weights of the remaining members of tho series unless it can be shown that a further a-particle which has. been overlooked, or a massive particle other than an a-particle, is expelled by some member of the series.Formerly T regarded the actinium series as beginning on a uranium isotope of mass 239 or 235 and ending at a lead isotope of mass 207. This view was suggested by the fact that the transformations ionium to radium-B, radiothorium to thorium-B, and radio-actinium to actinium-^, are all similar as regards the radiations expelled, and in that oa,ch product in these transformations has a period on the average 800 times smaller than that of its parent, and yet the average rate of decay of products of the first transformation is 7-5 x 103 times that of the corresponding products of the second and that of the second about 40 times that of the corresponding products of the third. I argued that as the factor 7-5 x 103 corresponds to a difference in mass of the isotopes of 2, then its square root (of the same order as 40) corresponds to a difference in mass of 1, I concluded, therefore, that if x, x - 2,. x - 4 represent atomic masses, and the first and second those of, say, ionium and radiothorium respectively, the atomic mass of radioactinium would be not x - 4 but x - 3.This implies, I see now, that the decreasing order of stability of tho masses is x, x - 2, x - 3, x - 4. But. if this order were x, x - 2, x - 1, x - 4, as I hope to show it is, then the proper conclusion from this relation between the periods is that the atomic mass of the actinium product is x - 1, not x - 3. The mass of radioactinium should be therefore 229, not 227, and, in consequence, that of every actinium product should be 2 units higher than I formerly thought. If protoactinium has an atomic mass of 233 the masses of actinium products of elements 92, 91, 90, 89, and 88 are known, and their stabilities may be compared with the corresponding products of the radium and thorium series. Two empirical relations appear to connect stability, as measured by half-value period, with mass.I. For an element of oven atomic number the masses of its a-ray and of its /3-ray isotopes are in decreasing order of stability when arranged in tho orders x, x - 2, x - 1, x - 4, x - 3, etc., and x, x + 2, x -I- 1, x + 4, x + 3, etc., respectively, x being an even number and the atomic mass of the stablest isotope.II. For an element of odd atomic number tho masses are in decreasing order of stability when arranged in the same order as the /9-ray isotopes of an element of even atomic number; x the atomic mass of the principal isotope is. however, an odd number. (For all radioactive elements the isotope of mass x is an 'o-rayer'; for a comparison of its stability with that of its /3-ray isotopes, however, it may be convention ally regarded as a '/3-rayer' of very long period and therefore of very great stability.) For element 92 the decreasing order of stability is uranium I (238), actinouranium (237), uranium II (234); by rule I. it is 238, 236, 237, 234, 235. For element 91 the same order is protoaotinium (233), uranium-2 (234), uranium-X2 (234); by rule II. it is 233, 235, 234, 237, 236. For element 90 the order is thorium (232), ionium (230), radiothorium - (228), radioactinium (229) for 'a-rayers'; by rule I. it is 232, 230, 231, 228, 229; for '/3-rayers' the order is thorium (232), uranium-.^ (234), uranium-Y (233); by rule I. it is 232, 234, 233, 236. For element 89 the order is stablest isotope (227), actinium (229), mesothorium-2 (228); by rule II. it is 227, 229, 228, 231. For these four atomic numbers, then, the rules give values consistent with the known or assigned values of all the known isotopes. A more general form of these rules holds for the isotopes of several of the inactive elements investigated by F. W. Aston. Granted that an element of even atomic number has one or more isotopes of odd mass number, then it is to be expected that (a) the even mass numbers may be arranged in order of decreasing stability in two series: one, in which the mass numbers increase uniformly from the mass number of the principal isotope, and the other in which the mas numbers decrease, (6) any odd mass number (capable of existing) when arranged with the even mass numbers in decreasing order of stability, follows the mass number one unit greater in an ' increasing ' series and the mass number one unit less in a 'decreasing ' series. For example, the experimental decreasing order of prevalence in Nature (here regarded as the criterion of stability) of the isotopes of selenium is 80, 78, 76, 82, 77, 74. The ' increasing ' series is 80, 82, the ' decreasing ' 80, 78, 76, 74, and the odd mass number follows 76, as it should according to the general form of the rule.Again, the experimental order for the isotopes of xenon is 129, 132, 131, 134, 136, 128, 130, which is nearly consistent with the orders given by the rule: 129, '132, 131, 134, 136, and 132, 130, 128. Of the elements investigated by F. W. Aston the experimental order of decreasing stabilities of isotopes is consistent with those given by the rule for sulphur, selenium, krypton, neodymium, and lead, is nearly consistent for xenon, cadmium, and mercury, and is inconsistent for tin and the light elements magnesium and silicon. In element 84, despite the fact that polonium has the longest period, the order of decreasing stability of the remaining isotopes is radium-^1 (218), thorium-^ (216), actinium-^4, radium-O' (214), and thorium-O' (2l2). By rule I. the atomic mass of actinium-4 should, therefore, be 217, and this leads to a value for the atomic mass of 209 for the end-product.In element 83 the stabilities of the three O-products may be compared first as ' a-rayers' and secondly as ' /3-rayers.' According to the rules, in the former case an atomic mass of 213 or 211 is suggested for actinium-O; in the latter case a mass of 213. These values lead to values of 209 and 207 respectively for the atomic mass of the end-product. In element 82 rule I. fixes the atomic mass of actinium- B as 211; for a mass of 213 the half-value period of actinium-B should be less instead of, as it is, slightly greater than that of radium-B; the value 211 leads to a value of the atomic mass of the end-product of 207.Finally, in element 81 rule II. gives possible values of 209 and 207 to the atomic mass of actinium-O", which lead to values of 209 and 207 respectively for the atomic mass of the end-product. On the whole, the application of the rules to these four elements, though not satisfactory, points to a value of the atomic mass of the end-product of the actinium series of 209 rather than 207. This is, of course, the value to be expected if protoactinium has an atomic mass of 233, and if there is no abnormal particle expelled by actinium-X or other member of the series.

ISSN:0028-0836    

DOI:10.1038/120402a0

出版商:Nature Publishing Group    

年代:1927

数据来源: Nature

摘要:

DURING recent investigations on the relation of spawning in the native oyster (O. edulis) to external conditions, certain phenomena, which it is advisable to record early, have recently been observed.At the end of the new moon tides at the end of July and in the beginning of August (1927), there was a fair to heavy general spawning of oysters (O. edulis) on the beds in the upper part of the Fal Estuary. In this general spawning it was observed that a large proportion of the spawning individuals had (apparently) failed to fertilise a large proportion of their eggs, varying in individuals from 20 per cent, to 60 per cent., with occasionally a higher proportion. The successfully fertilised eggs were found in the condition of development of 1, 2, or 3 days old embryos, while the unsegmented eggs showed at the same time great variation in size, and in many cases, bxit in small proportion, a variable number of nuclei to as high a number as 13. Unsegmented eggs containing many nuclei may be associated with either polyspermy, or with conditions which prevent segmentation after fertilisation, or may possibly also occur as a result of degenerative changes in the unfertilised egg. It is a fact, however, that there has been a large wastage of oyster eggs on the Fal Estuary oyster beds at the critical spawning time in early August.At the same time as it was found that a high percentage of eggs remained unsegmented, due apparently to not being fertilised, it was noticed that the percentage of incompletely spent female individuals had increased from an average of about 10 per cent, to 17 per cent, (in comparable samples each amounting to 700 individuals), so that eggs in considerable quantities have also been lost from an inefficient response to the spawning stimulus. . - The incomplete spawning of female oysters has previously been shown to be not uncommon (Jour. M.B.A., vol. 14, p. 974; 1927), and elsewhere (Fish. Invest., London, vol. 6, 3 and 4; 1924) that unspent ova may either remain in the gonad to produce a ' curdled fish,' and become absorbed later, or be excreted in masses on to the shell and covered with a calcareous deposit to form what Mr. Haynes, I believe, was the first to describe as an ' excretion blister.' The large proportion of incompletely spawned females recently found among the Fal Estuary oysters is nevertheless unusual, as is illustrated by the occurrence of only 2 to 6 per cent, incompletely spent individuals in more than 7 comparable samples of 100 oysters examined at the same time'from West Mersea, Essex. In one sample of 100 individuals from Thornfleet, West Mersea, however-and curiously on Aug. 2-there was the unusually high percentage for 1927 of 12 incompletely spawned. (These percentages are accumulative from the beginning of the spawning season.)The incomplete natural spawning of female oysters can probably be explained satisfactorily as a result of normal natural causes, and is probably always relatively high in the Fal Estuary. It seems highly probable that the phenomenon is due to the occurrenoe of temperature fluctuations at about the spawning period. Thus, this year it was found that the temperature over the Upper Fal oyster beds fluctuates to an unexpected extent with tho neap and spring tides; for example, on July 27 temperatures over the beds generally ranged from (j2° to about 63° F., the temperature being about 62° at 8-J fathoms at about low water above Turnawa-re Bar. On Aug. 3 at the same station at the same depth at half ebb-tide the temperature was below 60° and less that 59° at 14 fathoms at the lower end of the oyster beds. A similar fluctuation was observed in the succeeding neaps arid springs, arid on Aug. 17 the remarkably low temperature of 57° was recorded in 14 fathoms at tho lower end of the beds, with a corresponding reduction in temperature over the whole of the beds, it is clear, therefore, that at the spring tides relatively cold water sweeps directly into the Fal Estuary and over some parts of the oyster beds from the deeper parts of the English Channel, while during the neap tides the tidal oscillation of water is reduced and in summer weather the water becomes relatively warm. It is not possible, however, to discuss these matters and their bearing on spawning fully here. In samples of oysters from tho Fal Estuary, examined from one week to a fortnight after the abnormal spawnings were observed, individuals were found carrying normal shelled larva; and at the same time a small proportion of much smaller and frequently abnormal shelled larvao, the latter no doubt being the product of the fertilisation of scarcely ripe eggs; as the abnormal larvje will" probably not live, there will be additional loss of some of the eggs which were fertilised.It would seem, therefore, that at the period of the now moon tides at the end of July in 1927 on the Fal Kstuary oyster beds, there was a powerful stimulus exerted on oysters to spawn, and that a large proportion of those female oysters, which were approaching maturity, spawned either incompletely or apparently before collecting s'tifficient sperm to fertilise their eggs. Since normally segmenting om-bryos occurred alongside uiisegmented eggs in the mantle cavity of the same individual, it is not necessary to infer that abnormal substances in the sea-water have interfered with and affected the process of fertilisation. On the other hand, the occurrence of Jarge numbers of nnsegmenting eggs in a high proportion of the spawning oysters on beds which are depleted in numbers necessarily raises the question as to whether enough male-functioning oysters exist in the locality to supply the relatively widely scattered females. It is possible that not enough sperm had been emitted by the oyster population to enable those females ripening at the end of July and in early August to collect a sufficiency to fertilise their eggs. The lack of sperm may be due either to a, shortage of males or to an incorrect timing of the spawning of the males in relation to the maturing of the females. There is, however, no means of testing these views in this or a similar occurrence until further researches show at least how and when the native oyster stores the sperm destined to fertilise its ova,. Hoek, the great Dutch naturalist, found and figured in 1883 (Tijd. Ned. Dic.rk. Ver, Supp. Deel 1, Leyden) discrete sperm in tho renal tubules adjoining the external genital aperture in a female oyster, but the precise situation of this functional spermathcca has not yet been defined, nor has the condition of this region been determined in a significant number of ripening females to establish tho facts of the normal method of fertilisation in O. tidulia. A spermatheca which should contain enough sperm to fertilise any number of eggs from half a million to a million or more, in oysters of 5 years of age or more, ought not to be difficult to demonstrate.An additional point of interest arising out of the observations recorded above is that owing to tho large number of oysters which have spawned incom pletely, it is probable that there will be a slightly increased mortality, and also an unusual number of shells with excretion blisters in the form of sub- spherical calcareous projection containing rejected ova, as some newly formed ones have already been seen. From data which are being accumulated, evidence is being obtained that the incomplete spawning of females is a not uncommon cause of death, which will need to be considered carefully, in relation to occurrences of unusual mortality among oysters, especially when such occurs in seasons of abnormal we

ISSN:0028-0836    

DOI:10.1038/120403a0

出版商:Nature Publishing Group    

年代:1927

数据来源: Nature