摘要:

AbstractThemammals of the Paleocene, first epoch of the Tertiary, the Age of Mammals, are essential for the elucidation of numerous zoological, biological, and geological problems. Among these problems are determination of the affinities of mammals in general, of their ancestral and primitive structures and of the course of their evolution, as well as problems of the origin and nature of adaptations and habits, and more special and, in one sense, practical problems of stratigraphy and some other branches of geology.The first known Paleocene mammal was described in 1841, but intensive work began with Lemoine's first publication in 1878. Since that time work has continued at ever accelerated pace, by Cope, Osborn, Wortman, Matthew, Granger, Sinclair, Douglass, Gidley, Schlosser, Teilhard, Jepsen, Russell, Patterson, Simpson, and others. A nearly complete sequence of Paleocene mammalian faunas is now known from North America, and more limited but also important faunas are known from Europe, Asia, and South America.These faunas include multituberculates, marsupials and placental mammals, classified in seventeen orders, the general characters of which in the Paleocene are eviewed. From these mammals it is possible to infer with high probability the ancestral characters of placental mammals in general, the evidence for a primitive “tritubercular” or trigonal‐tuberculosectorial primitive molar type being particularly conclusive and important.The Cretaceous‐Paleocene transition in North America is marked by the disappearance of dinosaurs and the appearance of several orders of mammals apparently as immigrants from some unknown region. The Paleocene sequence on the same continent, which still has two breaks not represented by known faunas, is marked not only by great evolutionary advance but also by progressive enriching of the faunas, chiefly by the appearance of new and generally more progressive mammalian groups as immigrants. The Paleocene‐Eocene line is drawn at the culmination of this faunal change. Although in detail the change is by intergradation and gradual transition, from a broader point of view it marks a very radical difference in mammalian faunal type, the Paleocene forms eventually disappearing and the Eocene forms being the forerunners of the later Tertiary and Recent faunas. The same faunal change eventually occurred in South America, but at a much later date, around the end of the Tertiary.In the Upper Paleocene Asia, Europe, North America, and South America all show considerable local differentiation but give evidence of the derivation of their faunas from a common source. Those of North America and Europe are fairly similar, although not identical, and that of South America is most distinctive, evidence of longer separation from the other continents.In a general summary of known mammalian faunal history the few known Triassic mammals have no clear significance. The Jurassic mammals of Europe and North America are of distinctive type, with four primitive orders. From two of these developed the multituberculates, marsupials and insectivores of the Upper Cretaceous. Further differentiation of these three, but particularly of the general placental, carnivore‐insectivore stock produced the typical Paleocene faunal type. Finally, progressive evolution and diversification of the several Paleocene placental mammal stocks gave rise to the Eocene faunal type which still exists to‐day.Summary of Mammalian Faunal HistoryThe oldest known mammals, from the Rhaeto‐Lias in Europe and Africa, do not include the ancestors of the later mammals and have little bearing on mammalian faunal succession (see Simpson, 1928b). The Middle Jurassic fauna of England and the Upper Jurassic faunas of England, the United States, and East Africa (one specimen) are of a distinctive faunal type and suggest that this sort of mammalian fauna had then spread over a large part of the world. They include multituberculates, triconodonts, symmetrodonts, and pantotheres (Simpson, 1928c, 1929c). The multituberculates reappear, in more advanced and varied form, in the Cretaceous and Lower Tertiary. The triconodonts and symmetrodonts do not reappear and probably became extinct during the early Cretaceous. The known pantotheres seem to represent a Jurassic radiation from the common marsupial‐placental stock.The known Upper Cretaceous faunas also are of a distinctive faunal type, but one quite different from that of the Jurassic. They consist of multituberculates (Asia and North America), marsupials (North America), and very primitive placentals of rather undifferentiated insectivore‐carnivore type, classified as Insectivora (Asia and North America) (Gregory&Simpson, 1926; Simpson, 1928d). The latter apparently represent primary dichotomous differentiation of the general pantothere stock, with a secondary local radiation within each group.The known Paleocene faunas of North America, Europe, Asia, and South America probably all had a common source and represent the radiation of a fauna derived from one of the known Cretaceous types but much more highly differentiated. Among the multituberculates and marsupials this differentiation was of relatively minor grade, in taxonomic terms of family or at most subordinal rank, while the more progressive and adaptive placentals show the beginnings of a more profound splitting, ultimately of ordinal rank,1and are more numerous and varied. In North America, at least, this new faunal type appears as an invasion from some unknown evolutionary center.In Europe, North America, and Asia, a new type of fauna began to appear during the Paleocene, the change culminating at the end of the epoch and becoming entirely complete during the Eocene. The new fauna is less markedly different from the old than in the previous changes noted, and consists of the appearance of new or “modernized” groups clearly derived from an already partly differentiated fauna of Paleocene type. The new forms appear to be immigrants where found, and came from some unidentified area where the earliest Paleocene fauna was well developed and where its rapid and diversified evolution was permitted and stimulated. Only placental mammals were involved, the few surviving multituberculates and marsupials clearly being stragglers from the known Paleocene.There has not been any other major spread of mammals or great change in faunal type. With positive changes resulting from long evolution and from repeated intermigration and negative changes resulting from extinction, the mammals now peopling at least the Holarctic continents are essentially those that appeared there in the Eocene invasion. In South America this change was long delayed, and what is essentially the incursion of the Holarctic Eocene fauna into the previous habitat of the Paleocene fauna took place at the end of the Tertiary and not toward its beginning as in Holarctica. In Australia this change never took place (aside from the agency of man). The early faunal history of Africa is unknown and still be

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1937.tb01220.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1937.tb01221.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

摘要:

Summary1Solutions of crystalloids cannot be considered as substitutes for mammalian blood since they quickly leave the blood stream and are unable to maintain blood volume and pressure. This is true even of hypertonic solutions.2The only effective blood substitutes are those which contain sufficient colloidal material to give a colloidal osmotic pressure approximating that of normal blood. Blood plasma, blood serum, Ringer‐Locke solutions containing dissolved hemoglobin, and gum‐saline are the only substitutes of practical importance. Gelatine‐saline has also been used, but it is not now recommended.3Blood plasma is an effective substitute for much of the blood if the red cells in the mixture in the body are not too much reduced. Investigators are not agreed as to which organic constituent of blood plasma is most important. One group of workers supports the thesis that the plasma proteins are of major importance, another that it is the plasma lipoids which are most significant. Nearly all are agreed in the recognition of some organic colloidal factor.4Blood plasma is to be preferred to serum because of the formation, in the latter, of vaso‐dilator or constrictor substances, produced in the act of clotting. The vaso‐motor effects are partly chemical, partly mechanical in origin. Carefully prepared serum may, however, be used.5The oxygen capacity of the blood substitute is of vital importance. There is no substitute for hemoglobin. It must be present within the blood in a concentration of 3 per cent, or more, either within red cells, or dissolved in solution. The final mixture within the body cannot drop below this value.6When carefully prepared, properly balanced as to ion content, and well buffered, gum‐saline solutions furnish an effective blood substitute, particularly when washed red cells of the same species are suspended in the solutions. With solutions of the latter type it is possible to remove all of the normal blood and reduce the concentration of the normal plasma colloids to the vanishing point. In such total plasmapheresis there should be at least 30 per cent, of red cells added to the gum‐saline.7Difficulties arise in the use of gum‐saline for the following reasons:(a) The sedimentation rate of the red cells is greatly increased.(b) Gum appears to coat the red cells and considerably reduces their ability to combine with oxygen.(c) Gum leaves the blood stream with fair ease and cannot maintain the colloidal osmotic pressure of the blood for much more than 48 hours.(d) Gum is fixed in some of the tissues, particularly in the liver, and may be held in the body for as long as three years.(e) In association with its retention in the liver it is said considerably to diminish the concentration of the plasma proteins, possibly by blocking the liver.(f) It is chemically related to the antigenic polysaccharides produced by pneumococcus and other bacteria. Occasional instances of an antigenic action are on record, but these cases appear to be very rare.8In spite of these difficulties gum‐saline has had an increasing use in experimental work and clinical practice, and is to be highly recommended for many purposes.9Dissolved hemoglobin is not toxic to the vertebrate body if it has been properly freed from stromata, and if the solution is properly balanced. It is able both to carry oxygen and maintain the colloidal osmotic pressure. With such hemoglobin‐Ringer‐Locke solutions it is possible to wash out all of the normal blood and get mammalian preparations practically doid of all cellular components in the circulating fluid. Oxygen consumption continues at the normal level. Hemoglobin in solution, however, leaves the blood vessels rather quickly, passing into lymph and urine, and being taken up by cells of the reticulo‐enthothelial system. It is also slowly changed into methemoglobin. It is not able, therefore, to maintain life for more than 36 hours after c

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1937.tb01222.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

摘要:

Summary1Digestion in the primitive animals must have been intracellular, as it remains in the Protozoa and in the Porifera. It has persisted, to a greater or less extent, in a number of Metazoa. These may be divided into two groups: (1) those which are primitive in structure,e.g.Coelenterata, Ctenophora, most Turbellaria, andLimulus; and (2) those which are more highly evolved but have retained intracellular digestion in correlation with their mode of feeding,e.g.Brachiopoda, Rotifera, Tardigrada, Pyncogonida, Arachnida (other thanLimulus) and the majority of Mollusca excluding the Cephalopoda. These animals either feed on finely divided food (collected by ciliary mechanisms or scraped by a radula) or on fluid or semi‐fluid food which is sucked in.2In certain cases, notably the Lamellibranchia, but also in the Echinodermata, intracellular digestion is assisted or exclusively carried out by wandering phagocytic blood cells.3Extracellular digestion, originally developed with the increased size of available food as an aid to intracellular digestion, has completely replaced the more primitive form of digestion in certain rhabdocoel Turbellaria (probably), Polyzoa, Annelida, Myriapoda, Crustacea, Insecta, Cephalopoda and Chordata. This mode of digestion results in the reduction of the ingestive region of the gut and enables digestion, and the removal of indigestible material, to be hastened. The resultant increase in the rate of metabolism has had profound effects on the evolution of the Metazoa.4The appearance of extracellular digestion has been accompanied by changes in the structure and physiology of the gut. Distinct regions have been specialized for (1) the reception of food, (2) its conduction and storage, (3) digestion and internal triturition, (4) absorption, and (5) conduction and formation of faeces.5There is a definite correlation between the food of any animal and the nature and relative strengths of its digestive enzymes. Certain animals have acquired specific enzymes which enable them to exploit additional sources of food, the most important of such enzymes being cellulase and chitinase.6There is a periodicity of secretion in the digestive glands of many Metazoa,e.g.Gastropoda and Crustacea. In the Lamellibranchia and in style‐bearing Gastropoda, the style constitutes an ideal mechanism for the continuous liberation of small quantities of enzyme (amylase).7ThepH of the gut is controlled in various ways in different phyla. In ciliary‐feeding animals this may be of importance not only in securing the optimum conditions for the action of extracellular enzymes but also by its influence on the viscosity of the mucus with which the food is entangled.8There is evidence that the time taken for passage of food through the gut at any normal temperature corresponds to the period which is optimal for enzymatic action at that particular temperature.9The most successful groups of animals are (1) those which possess feeding and digestive mechanisms capable of utilizing, as a result of morphological and physiological adaptations, many types of food,e.g.Annelida, Crustacea, Insecta, Gastropoda and Vertebrata, and (2) those in which one type of food is collected and digested with great efficiency,e.g.Coelenterata, Turbellaria, Arachnida, and Cephalopoda (carnivorous); Brachiopoda, Lamellibranchia, and Tunicata (ciliary feeders); Trematoda and Cestoda (parasites). Of these, the first have been by far the more successful, owing to their capacity for exploiting new sources of food, in the invasion of new hab

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1937.tb01223.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1937.tb01224.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

摘要:

V. ZUSAMMENFASSUNGBerichtet wird über Phänomene des Bewegungssehens die an Menschen und Tieren festgestellt sind. Visuell wahrgenommene Bewegung liegt vor, wenn einem optischen Wechsel in der Umgebung, bei alleiniger Vermittlung des Lichtes, eine Reaktion entspricht, die je nach dem Stand dieses Wechsels spezifisch gerichtet ist.Verschiedene Sinneselemente machen infolge geometrischer Veränderungen in der Umgebung einen Belichtungswechsel durch, so dass an Stelle einer objektiv kontinuierlichen Verschiebung eine Folge von Erregungen im Rezeptor auftritt (reelle Bewegung). Werden dabei einige Elemente, die in den Bereich der Erregungsverschiebungsbahn fallen, übersprungen, so ändert das unter gewissen Bedingungen nichts am Effekt (Kinematoskopie). Bleibt ein Bereich in einem umfassenden optischen Wechsel konstant, so erfolgt die Reaktion oft so als ob der konstante Bereich sich verschoben hätte und der umfassende Wechsel constant geblieben wäre (induzierte Bewegung).Bewegungssehen unter experimentellen Bedingungen an Tieren hat zuerst Doflein an Dekapoden nachgewiesen. Wird die Umgebung optisch verschoben, so treten optomotorische Reaktionen auf, die ausser von Wirbeltieren auch von höheren Insekten ausgeführt werden, nicht aber von Coccinellen, die nur Lagekorrekturen ausführen (Gaffron).Wolf stellt die optomotorischen Reaktionen an Bienen fest und weist nach, dass Bienen schnelleren Reizwechsel dem langsameren voniehen. Hertz erbringt den Nachweis, dass diese “Flimmertaxis” nicht als Grundlage des Bewegungs‐ und Formsehen anzusehen ist, wie Wolf annimmt. Fliegen können ruhende und bewegte Muster auch dann unterscheiden, wenn erstere infolge der Körperbewegung des Tieres ebenfalls eine Lichtverschiebung auf dem Lichtsinnesorgan hervorrufen.Bewegungsschwellenbestimmungen wurden ausser an Arthropoden auch an Hühnern und an Ratten ausgeführt. Uexkülls Schule hat die Verschmelzungsgrenzen und die Schwellen für langsamste und schnellste Bewegung am KampffischBettafestgestellt und nachgewiesen, dass eine Bewegung fürBettaungefähr zweimal so schnell erscheint wie für den Menschen. Es besteht also ein Unterschied in dem zeitlichen Auflösungsvermögen der verschiedenen Organismen. Dieses Auflösungsvermögen ist von der Chronaxie, der Refraktärphase und der Latenzzeit abhängig.Die kinematoskopische Bewegung ist von der reellen nicht unterscheidbar (v. d. Waals u. Roelofs). Sie soll nach der Produktionstheorie durch die Phantasie entstehen. Unter den Beweisen, die für eine physiologische Entstehung des Phänomens sprechen, nehmen die Alternativversuche eine wichtige Stellung ein. In Situationen die zwei Bahnen ermöglichen, lasst sich auf Grund einfacher Figuralgesetze voraussagen welche eintreten wird (Schiller). Die Kinematoskopie ist auch für Wirbeltiere nachweisbar, wie das Gaffron mit der optomotorischen Reaktion und Schiller mit Dressurversuchen anPhoxinusgezeigt haben. Die genannten Forscher weisen aber mit verschiedenen Methoden nach, dass Arthropoden (Aeschna, bezw.Galathea) kein kinematoskopisches Sehen besitzen. Das Komplexauge ist also für die Organisation von Bewegungen aus diskreten Reizen nicht geeignet.Die induzierte Bewegung lässt diejenige Raumstelle bewegt erscheinen, die in einem Bezugssystem lokalisiert ist (Duncker). Im Falle einer umfassenden Bewegung der Umgebung wird der Körper des Beobachters ds bewegt erlebt. Gaffron weist die induzierte Bewegung beiAeschnanach, indem dieses nur auf bewegte Objekte jagende Tier die Fangreaktion ausübt wenn hinter einem ruhenden Fleck, auf den es sonst nicht reagiert, ein Streifenmuster vorbeigezogen wird.Unter den physiologischen Theorien sind die von Hertz und von Köhler für reelle und induzierte bezw. für kinematoskopische Bewegung behandelt. Nach Hertz ist das physiologische Korrelat des Bewegungssehens in der Erregungsasymmetrie zu suchen, die während des Erregungsfortschreitens im Sinnesfeld entsteht. Nach Köhler besteht eine gegenseitige Anziehung der Erregungsströme bei diskreter Reizlage, die für das einheitliche Sehen der Bewegung verantwortlich ist. Verfasser modifiziert diese Hypothese in dem er einen tonischen Vormeldungsprozess annimmt, der die Entwicklung des vorangegangenen Erregungsvorganges beeinflusst. Diese Annahme wird an den Alternatiwersuchen und an von Rubin entdeckten Phänomenen antizipatorischer Art veranschaulicht.Je nach der zeitlichen und räumlichen Gliederung des Umfeldes und je nach den Auflösungsverhältnissen der Sinnesorgane—sowohl in der bekannten räumlichen, wie in der hier entwickelten zeitlichen Hinsicht—entsteht entweder die Wahrnehmung von diskreten, oder von einheitlichen VorgängenSummaryMovement‐vision (i.e. the visual perception of changes in the geometrical arrangement of the light pattern of the environment) in man and animals has been dealt with in this review.A change in the geometrical arrangement of the light pattern is said to be visually perceived when it calls forth a reaction which is determined in its direction by the nature of the change.Inreal movement‐visiona number of sensory elements in an eye, as the result of the pattern changes in the surroundings, undergo a change in illumination, and, in consequence of the mosaic structure of the retina, there arises in it a series of discrete excitations. If certain sensory elements of the retina which fall in the path of the moving excitation are not stimulated, and the animal nevertheless reacts as in the case of real movement‐vision, we then speak ofkinematoscopy.If a certain restricted region of a field of vision does not move when the rest of it is in motion, an animal often reacts as if the stationary region were moving while the part of the field actually in motion remained stationary: this is spoken of asinduced movement‐vision.Movement‐vision was first experimentally demonstrated by Doflein in decapod crustaceans: if the surroundings move, optokinetic reactions ensue. Such reactions also occur in vertebrates and insects, although coccinellids only react by changes in posture.Wolf demonstrated optokinetic reactions in bees. He also showed that these animals respond better to quick than to slow changes of stimulus. Hertz proved that this so‐called “flickertaxis” is not the basis of movement‐vision and form‐vision, as Wolf assumed. Flies can distinguish stationary from moving patterns, even when the former produce a displacement of light on the retina as a result of the animal's own bodily movement.Thresholds for the perception of movement have been studied in arthropods, fowls and rats. Experiments by Uexküll's school have shown that a given movement would appear about twice as quick to the fighting fish,Betta, as it does to man. Thus the resolving power for consecutive optical stimuli varies in different animals. This temporal resolution depends on chronaxie, refractory period and latent period.Kinematoscopic movement cannot be distinguished by the animal from real movement. According to the “Produktionstheorie” the apparent identity of the two is due to the imagination. Amongst the proofs of a physiological origin of the phenomenon, experiments with alternating images take a prominent place. When it is possible for an image to follow one of two virtual paths, it can be predicted by simple rules which path will be adopted. Kinematoscopy has also been demonstrated in vertebrates by optokinetic reactions and by training experiments. It has been shown, however, by various methods, that arthropods have no such kinematoscopic vision. Thus the compound eye is not suitable for the synthesis of movements from discrete stimuli.Induced movement‐vision causes a stationary region in space to appear to be in motion, whenever that region assumes a certain importance relative to its moving surroundings; when a considerable portion of the surroundings is in motion, an observer has the sensation of being in motion himself. It has been shown that a similar induced movement‐vision exists in the dragon‐fly,Aeschna, which hunts moving prey; if a striped pattern is moved behind a stationary spot, the latter calls forth the atoscopic movement‐vision, those of Hertz and Köhler have been reviewed. According to Hertz, the physiological explanation of movement‐vision is to be sought in asymmetry of stimulation arising during the progression of the stimulation across the sensory field. According to Köhler a mutual attraction between streams of excitation arising from two discrete points of stimulation is responsible for uniform movement‐vision. The author has modified Köhler's hypothesis by assuming a tonic heralding process influencing the effect of preceding excitation. This assumption is supported by experiments with alternating images and by other anticipatory phenomena discovered

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1937.tb01225.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1937.tb01226.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY