ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 427 



variable. This anterior cavity is broader and lower than the spinal 

 canal. It is lined by epithelium which is continuous with that of the 

 latter. An account is given of the olfactory nerve, the frontal organ, 

 the pigment spot and its nerves, the ganglionic dorsal apparatus, and 

 the dorsal giant cells of the frontal section — the oblongata of authors. 



Growth and Renewal of Dermis.* — -Ed. Retterer concludes that the 

 phenomena of embryonic development and adult histogenesis are practi- 

 cally the same as regards the dermis. The germinal epithelium furnishes 

 superficially the mucous or corneous elements, and, internally, the cells 

 which are transformed into denser connective tissue (dermis) and reti- 

 cular tissue (lymphoid). The epithelium is the initial tissue, forming 

 epidermic elements which are desquamated off, and deeper elements 

 which form, add to, and replace the constituents of the dermis. 



Pathological Nature of Holmgren's Canaliculi in Nerve Cells. f 

 R. Legendre maintains that the " Saftkanalchen " which Holmgren 

 described in 1900 in the snail — fine prolongations from interstitial cells 

 entering the nerve cells — are well-known neuronophagous phenomena, 

 due to a kind of phagocytosis on the part of the neuroglia cells. 



Structure of Gas-Gland in Swim-Bladder.l — Karolina Reis and 

 J. Nusbaum give an account of the minute structure of the epithelial 

 body or gas-gland of species of Ophidium, and of the disruptive process 

 by which gas is evolved. They also discuss the " oval " which functions 

 as an elastic pressure-regulator, evaginating and invaginating, and 

 thereby affecting the gaseous content of the bladder. 



Whitening of Hairs and Feathers in Winter.§ — El. Metchnikoff 

 adheres to his previous conclusion that " chromophagous " cells transport 

 the pigment from hairs into the skin or to the surface. The theory that 

 the blanching is due to gas cannot suffice, for the gas is only in the 

 medullary portion of the hairs. He has made observations on Lepus 

 variabilis, Lagopus albus, and L. alpinus, on a hen which began to turn 

 white, and has found the chromophagous cells at work. 



Shape of Human Erythrocytes. ||— H. E. Radasch finds that the 

 majority of the erythrocytes in the circulating blood of fcetus and adult 

 are bell-shaped. On exposure to air the bells collapse and become disks. 



c. General. 1 



Origin of the Deep-Sea Fauna. f — A. E. Ortmann argues that the 

 present deep-sea fauna — adapted to very low temperature — must have 

 had an origin subsequent to the polar cooling, which probably occurred 

 in Tertiary ages. Part of the fauna may be autochthonous, adapted 

 from previously existing Mesozoic or pre-Tertiary forms which had 



* Journ. de l'Anat. Physiol, xlii. (1906) pp. 297-304. 

 f Comptes Rendus, cxli. (1905) pp. 1265-7. 

 % Anat. Anzeig., xxviii. (1906) pp. 177-91 (2 pis.). 

 § Comptes Rendus, cxlii. (1906) pp. 1021-8. 

 H Anat. Anzeig., xxviii. (1906) pp. 600-4. 



4 Eighth Internat. Geograph. Congress, 1905, pp. 618-20. See also Zool. 

 Zentralbl., xiii. (1906) pp. 302-3. 



2 F 2 



