摘要:

Summary.An illustrated account is given ofPlasmodium relictumn. var.spheniscidæfrom the King Penguin,Aptenodytes patagonica, from South Georgia, the Black‐footed Penguin,Spheniscus demersus, from Saldanha Bay, South Africa, the Yellow‐crowned Penguin,Eudyptes antipodes, from Foveaux Strait, New Zealand and the Rock‐hopper Penguin,Eudyptes crestatus, from Gough Island.The variations in the morphology and in the range of dimensions of thePlasmodiumfrom each of the hosts are described and illustrated. Detailed comparison shows that the same organism is present hi all of them.The effects ofPlasmodium relictumvar.spheniscidæon the hosts are described in some detail, counts of infected erythrocytes and of parasites are given and the effect of alterations induced in organs of one Black‐footed Penguin are discussed. The parasite level in the different hosts is noted.The identity of thePlasmodiumfrom the four species of Penguin is discussed in some detail, especially in view of the wide distribution ofPlasmodium relictumGrassi and Feletti both geographically and in the number and variety of its hosts. Various morphological and physiological strains ofP. relictumare noted and induced morphological differences by passages to unusual hosts are considered. The conclusion is reached that a strain or morphological variety ofP. relictumis present in Penguins, for which the namePlasmodium relictumn. var.spheniscidæis proposed.The low gametocyte level ofP. relictumvar.spheniscidæin all the hosts seems to indicate that it may be approaching natural agametogony, and so may be on the way to self‐extermination.Tolerance and age‐immunity of hosts and possible susceptibility and immunity among Culicine mosquitoes in relation to avian malaria are briefly noted.The economic importance of avianPlasmodiumin general, and possibly ofPlasmodium relictumvar.spheniscidæis b

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1944.tb00222.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1944.tb00223.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1944.tb00224.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1944.tb00225.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1944.tb00226.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

Summary.Proteocephalus varius(Beddard, 1913) is redescribed from specimens obtained fromVaranus komodoensis, andP. sandgroundiCarter, 1943, is regarded as a synonym of it. An unsuccessful attempt to elucidate the life‐history of the species is describe

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1944.tb00227.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

Summary.1If the waves or impulses started at thetipof the flagellum in a mono‐flagellate organism, and travelled towards the base, the flagellum would obviously be held out in an extended position and draw the cell after it. This is the old and mistaken concept of thetractellumas described by Gray. It appears to be the result of deduction rather than observation or experiment, though surely the waves are more likely to start at the base of a flagellum than at the tip.2It has been proved, largely by means of high‐speed photomicrography, that the waves do start at the base of the flagellum, and not at the tip, in all organisms so far investigated, and hence the whole mechanical concept of the system requires drastic alteration.3In 1925 Krijgsman examined the movement of the longer flagellum ofMonasby means of dark‐ground illumination. He clearly recognized that the waves started at the base of the flagellum; but since in his observations the organisms were placed in a compressor or were mounted in a drop of fluid between slide and cover‐slip, their movements were restricted and they were able to swim at only about one‐tenth of their normal speed.4The majority of the Monadaceæ swim rapidly, and one species,Monas stigmaticaPringsheim, covers a distance of forty times its own length in a second.5Krijgsman's paper constituted at the time a valuable contribution to our knowledge of flagellar movement, but it gives a totally wrong conception of the movements of the free‐swimming organism.6In flagellate organisms which swim forward rapidly, or cover several times their own length per second, e. g.Monas stigmaticaorPolytoma uvella, the flagellum, or flagella, in which the waves start at the base, cannot be held in the extended position during normal swimming. They must be reflexed or bent backwards, and their function is to cause the organism both to rotate and gyrate. It is this rotation and gyration which provides the forward component.7In very slow‐swimming flagellate organisms, however, and especially in the colonial flagellates such asVolvoxsp., the flagella are held out in the extended position and may precede the organism. The mechanics of the flagellar movement in this type of flagellum has been investigated experimentally and described.8The well‐known flagellate organismPeranemaalso moves forward very slowly, with the greater part of its single flagellum extended, but even so the tip of the flagellum is reflexed. However, it is doubtful whether the flagellum has any locomotory function in the normal movement of this organism.9The waves start at the base of the flagellum and not at the tip (Lowndes, 1936).10When stimulated by the shaking of the slide or by an electric shock, etc., the whole of the flagellum ofPeranemais thrown into a succession of waves, but under these conditions the organism stops moving forward. It changes its direction and then proceeds as before.11These observations are in complete agreement with those of Verworn.12It is usually stated in text‐books,e. g.Gray (1928) and Borradaile and Potts (1941), thatPeranemaswims slowly forward when the waves in the flagellum are confined to the tip, but that it swims rapidly forward when the waves occur throughout the whole length of the flagellum. Verworn is usually held responsible for this statement, though he actually stated nothing of the kind. His observations were correct, while their more recent interpretation has been shown to be incorrect.13One of Krijgsman's diagrammatic figures has been reproduced by itself in more or less advanced British text‐books, and hence it is finding its way into the elementary text‐books. The figure in question is shown in fig. 1 B. It was originally given as a simplification of two other figures, and in conjunction with these and with its proper context it was perfectly sound, but taken by itself, and away from the proper context, it constitutes what can only be described as a travesty o

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1944.tb00228.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

Summary.The reproductive cycle of the female weasel (Mustela nivalis) has been studied by the examination of the ovaries, uterus, etc., in 114 animals killed in the field. Some additional weasels were kept in captivity for periods varying up to sixteen months. Pregnancies are most common in April or May, but they will occur in any month from March till August. Weasels having their first litter in the spring can breed again in the summer. The majority of weasels do not breed until their second season, but some born in spring become pregnant in late summer. Anœstrus commonly lasts from September till February, but in individual animals the first œstrus may not occur until May or even June. It is estimated that pregnancy and lactation together last about 10 weeks. Histologically, the reproductive organs resemble those of the ferret and stoat. The number of corpora lutea in the two ovaries varies from 4–11, with an average of 7. Six or seven fœtuses were found in the small number of pregnancies in which they could be counted. It seems probable that in the weasel ovulation is dependent upon copulation.The collection of weasels described in this paper was begun by Dr. A. S. Parkes, F.R.S., in 1930, and later continued by Dr. M. Hill. I am much indebted to Dr. Hill for transferring to me her sectioned material, with extensive records, notes, measurements anti micro‐photographs, when circumstances made it impossible for her to complete the work. The micro‐photographs, except for two, are the work of Mr. F. J. Pittock.Rather more than half the female weasels were obtained through the co‐operation of Professor F. W. R. Brambell, and his continued help has been greatly a

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1944.tb00229.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

Summary.This paper is based on the examination and identification of all the larva and adult Elateridæ occurring in soil samples taken from 1871 fields in the Mid‐ and West Wales province. All the species found are listed, together with some additional species discovered by general collecting in the Aberystwyth district.The most important Elateridæ areAgriotes obscurus, A. lineatus, A. sputatorandCorymbites cupreus. Athouslarvæ are not particularly common, and only 15 fields were noted in which the population ofAthouslarvæ exceeded 100,000 per acre. In isolated instancesCorymbites tessellatus, a small species ofCorymbitesof uncertain identity, andCryptohypnus ripariusoccurred in numbers sufficient to constitute a possible danger to crops.There is little definite relation between the total Elaterid population and the altitude of the land sampled; considering the province as a whole there is an indefinite tendency for the population to rise with increase in altitude. Its composition changes with elevation, particularly in fields over 1000 ft., where the relative proportion of the population made up by the three common species ofAgriotesdrops from the 95·4 per cent. characteristic of lowland fields to 62·8 per cent. In such fieldsAgriotesis extensively replaced by species ofCorymbites, particularlyC. cupreus; in a high proportion of fields over 1000 ft. and in many fields with an altitude of 600–1000 ft.cupreusis probably an important pest.Of the three common species ofAgriotes, obscurusis generally the most abundant andsputatorthe least, as far as can be gathered from records of adult beetles occurring in the soil samples.Obscurusis the dominant species at all altitudes, particularly in high ground, whilesputatorappears to be a lowland species, becoming rare in fields over 600 ft. and absent above 1000 ft.The average total Elaterid population for the area is 218,800 per acre. 117 fields with populations of 600,000 to 999,000 were recorded, and only 28 with populations of 1,000,000 and above. There is some evidence suggesting that with increase in the total population there is a tendency forAgriotesto form an increasing proportion of the population to the exclusion of other species, and also some evidence suggesting that fields of high population tend to be grouped

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1944.tb00230.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1096-3642.1944.tb00231.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY