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doi: 10.1111/j.1096-3642.1958.tb00693.xpmid: N/A
1 Post‐mortem examination of female house mice from a confined population showed a higher proportion of non‐fecund females than would be found in a wild‐caught sample of similar age composition. 2 A similar population was allowed to disperse into a larger pen, whereupon the reproductive rate increased. The result was not clear‐cut, however, as the increase began too soon to be attributable to dispersal alone. 3 Another similar population was divided into two colonies of unequal size. Non‐fecund females transferred to a new large pen with few other mice became fecund and reproduced successfully, while those placed in a new small crowded pen remained non‐fecund. 4 A completely adult population in which no litters had been born for over six months was allowed to disperse into a large pen. A majority of females became fecund and conceived within about one week. The numbers were doubled within eight weeks. 5 The results suggest the existence of a self‐regulatory mechanism, which operates at population densities seldom, if ever, reached in free‐living populations.
doi: 10.1111/j.1096-3642.1958.tb00694.xpmid: N/A
1 The distribution of RNA, fats, iron, glycogen and alkaline phosphatase in the endometrium, yolk‐sac placenta and decidua of Talpa europaea is described. 2 The areolae which are formed are associated, at first, with the vitelline circulation and are probably important sites for the uptake of iron—derived from maternal erythrocytes, protein and saliva insoluble carbohydrate material derived from the secretions of the adjacent uterine glands. The aerolae persist into late pregnancy in association with the allantoic circulation. 3 A vascular yolk‐sac placenta is formed in early pregnancy but it is probably not of any real significance in embryonic nutrition—with the exception of the areolae mentioned above. It is evident that the structural changes which occur in the uterine wall during the formation of this placenta are essentially preparatory to the subsequent establishment of the allantochorionic placenta. 4 Stainable glycogen is absent from the decidual tissue and little lipoidal material is present except in the symplasma which invests the trophoblastic villi. 5 The avascular yolk‐sac placenta, the progressive establishment of which is described, is concerned with the absorption of protein, saliva insoluble carbohydrate material and other substances contained in the secretions of the uterine glands of the mesometrial wall of the uterus. The uterine secretions are of considerable importance in embryonic nutrition and probably continue to be of some significance even in late pregnancy. 6 The yolk‐sac increases in volume up to about the 11·5 mm. stage and the concentration of protein in its fluid at this stage is about 60 per cent of that in the maternal serum. In late stages the concentration of protein in the fluid is greater than that in the maternal serum. Fibrinogen is absent from the fluid in Talpa. 7 The yolk‐sac fluid could serve as an important source of absorbable material and it is probable that the yolk‐sac splanchnopleur, the histochemical and histological properties of which are described, is of some significance EM a placental structure in this species. 8 Reichert's membrane is formed in the avascular wall of the yolk‐sac in early pregnancy and it attains a thickness of about 3 μ in late stages. Its histochemical and tinctorial properties resemble those which have been described for the membrane in the rat and hedgehog and; EM in these species, it is formed of collagenous material. In Talpa the membrane is probably of endodermal origin.
doi: 10.1111/j.1096-3642.1958.tb00695.xpmid: N/A
The behaviour of twenty‐seven species of estrildine finches is concisely reported. Brief information is also given about the geographical distribution and the comparative morphology of the Estrildinae. Ethological, geographical and morphological data are then combined in a discussion of the evolution of the group, and finally some minor taxonomic revisions are suggested.
MARSHALL, N. B.; THINES, G. L.
doi: 10.1111/j.1096-3642.1958.tb00696.xpmid: N/A
1 The structures of the brain and sense organs of Typhlogarra widdowsoni, a blind cave fish from Iraq, are described and compared with those of Garra rufa, the nearest related species. 2 In Typhlogarra the optic lobes and eyes are very regressed. Only the lateral parts of the optic tectum are developed and these incompletely. The optic nerves do not connect with the brain and the different parts of the eye are not easily recognisable. 3 Experiments on the light sensitivity showed that Typhlogarra is slightly photonegative, but indifferent to the wave length. It is quite unlike Caeco‐barbus geertsi, a, blind cave fish from the Belgian Congo, which is markedly photonegative. Other differences in behaviour are also considered 4 More general comparison of Typhlogarra with other blind species re‐emphasises that such fishes are remarkably diverse in their biology.
doi: 10.1111/j.1096-3642.1958.tb00697.xpmid: N/A
1 The maxillary nerve has been dissected throughout its course in representatives of the Prosimii (tree shrew, lemur, loris and galago); the Ceboidea (New World monkeys); the Cercopithecoidea (Old World monkeys), and the Hominoidea (chimpanzee, orang‐utan and man). 2 The maxillary trunk gives off the zygomatic and superior dental nerves before splitting at a variable point into nasal and labial divisions. The first is distributed to the side and vestibule of the nose and supplies the rhinarium if present. The second is distributed to the mystical vibrissae (if present) and to the skin of the cheek and upper lip—some of its branches being faaciculated with twigs of the facial nerve. 3 In the Prosimii, where a rhinarium is associated with an uncomplicated facial musculature, the nasal division is the bigger. Relatively few fibres of the labial division are fasciculated with twigs of the seventh nerve. 4 In monkeys where the rhinarium has disappeared and the facial musculature has increased in complexity, the labial division is the bigger and more of its fibres are associated with twigs of the facial nerve. In certain New World monkeys (Lagothrix, Saimiri and Ateles) many of these presumably proprioceptive fibres travel via the zygomatico‐facial nerve. 5 The further elaboration of the facial musculature in apes results in still more fibres being fasciculated with twigs of the seventh nerve, while in man, the trend continues further and the infraorbital plexus is more extensive than in any lower primate.
doi: 10.1111/j.1096-3642.1958.tb00698.xpmid: N/A
1 The numbers and arrangement of infraorbital foramina have been recorded, and their position relative to the orbital and alveolar margins defined by measurement in 205 gorillas, 178 chimpanzees, 82 orangutans, 64 gibbons and 192 men of various ages. 2 In man there are, on an average, 1·05 infraorbital foramina in each maxilla; in the gibbon 1·2; in the gorilla 1·6; in the chimpanzee 2·4; and in the orang‐utan 3·3. 3 In adult men and gibbons the distance between the infraorbital foramen and the orbital margin is about twenty per cent of that between the foramen and the alveolar margin. The corresponding figure for the gorilla is forty‐five per cent, for the chimpanzee forty per cent and for the orang‐utan thirty‐five per cent. 4 The arrangement of the infraorbital apertures varies widely both within and between species. 5 While the milk teeth are erupting, the infraorbital foramen lies relatively nearer to the inferior orbital margin than in adults. In man, chimpanzee and gorilla, the adult position is reached by the time the first permanent molars are in line. In the orang‐utan, the position of the foramen apparently continues to change until maturity is reached. 6 The numbers and arrangement of the infraorbital foramina are not correlated with the more obvious facial features (such as degree of prognathism), nor with variation in the basic subdivisions of the infraorbital nerve. 7 The position of the foramen relative to the orbital and alveolar margins is closely related to the degree of prognathism. 8 Although a single aperture appears to have occurred more frequently in the Australopithecinae than in the extant great apes, the foramen in these fossils lay in a position characteristic of the gorilla, and much further down the facial skeleton than in either modern man or the extinct species Homo neander‐thalensis.
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