ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 13 



be principally related in both sexes to the genital function. Evidence 

 is supplied by a law of seasonal alternation of these functions as 

 illustrated in Helix and Limax, in Aster ias, and in Vertebrates at the 

 time of gestation, of suckling, and the beginning of embryonic life. 

 Histological studies reveal the migration of the fat from the hepatic to 

 the genital glands in various molluscs, in Astacus and Garcinus ; and in 

 higher animals the arrangement of the fat at the level of the supra- 

 hepatic centre in the mother, and at the level of the portal vein in the 

 foetus, indicates the passage of this fat from the liver of the mother to 

 that of the foetus. 



Tympanic Region in Mammals.* — P. N. van Kempen has made 

 an exhaustive study of the structure of the tympanic region in the 

 mammalian skull. He discusses the development of the cavities and 

 bones connected with the region, the associated nerves and blood-vessels, 

 and the various conditions found in the different orders of mammals. 

 Primitively the tympanic was a narrow ring, incomplete above, in an 

 almost horizontal position, with its ventral wall closely apposed to the 

 skull. The evolution from this primitive condition is traced in detail. 

 The author maintains that the entotympanicum is quite peculiar to 

 mammals, without representative in lower Vertebrates, and that the 

 tympanic is derived from a membrane bone of the lower jaw, probably 

 the supra-angular. 



Evolution of Tertiary Mammals.f — Ch. Deperet takes a survey of 

 the various Eocene faunas of Tertiary mammals, and seeks to gain some 

 greater clearness as to the actual phylogenetic events by distinguishing 

 such evolution as took place in the area in question from the results of 

 migrations from distant centres of dispersal. 



Bronchial Tree in Birds. | — G. Fischer gives a comparative account 

 of the bronchial tree in birds. A lower ventral and an upper dorsal 

 region, grouped round the main bronchus, are sharply distinguished. 

 The ventral region is very regular, with 8 passages (bronchi) of large 

 calibre. The dorsal region is more irregular and variable, with 6-10 

 bronchi. The large bronchi tend to spread on the external surface of 

 the lung ; the main internal mass is formed from the bronchi fistularii. 

 The pulmonary artery branches for the most part dichotomously, and 

 the stronger vessels extend between the ventral and the dorsal regions. 

 Round the lumen of the individual bronchi fistularii, short compressed 

 bronchioles are radially disposed ; they branch dichotomously and form 

 an air-capillary network with numerous canals of equal width. These 

 air-capillaries form a network with the blood-capillaries. 



All the air-passages anastomose. There are no blind-sacs or alveoli. 

 There are some interesting adaptive differences between the lungs of 

 aquatic birds and land birds, between good fliers and poor fliers. 



Toxicity of Eggs. § — G. Loisel finds that the yolk of the eggs of 

 the fowl, the duck, and the tortoise contains toxic substances which, 



* Morphol. Jahrb., xxxiv. (1905) pp. 321-722 (96 figs.), 

 t Comptes Rendus, cxli. (1905) pp. 702-5. 

 X Zoologica, xix. (1905) pp. 1-45 (5 pis. and 2 figs.). 

 § Comptes Rendus, cxli. (1905) pp. 733-4. 



