ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 563 



the afferent artery consist of : — (1) the endothelium, (2) the elastica of 

 the intima, and (3) the muscular envelope. The walls of the efferent 

 artery consist of : — (1) the endothelium, and (2) the muscular envelope. 

 This difference was seen in ten different Mammals, and is related to a 

 functional difference. 



Structure of Myocardium.* — E. Retterer and A. Lelievre has 

 studied this in tench, frog, and tortoise. The cells of the myocardium 

 have, besides the nucleus, a chromophilous and elastic framework. In 

 the interval between two cells the elastic framework is most developed, 

 and it gives off lateral " ramusculi " which penetrate into the fibre-cells, 

 becoming continuous with their chromophilous and elastic reticulum. 

 The inter trabecular " bandelettes " of the fibre are partitioned by the 

 lateral ramusculi or stria? of Amici. 



c General. 



Experimental Biology. j — Hans Przibram has discussed in a lecture 

 the application of experimental methods in relation to the fundamental 

 questions of biology. He refers to such instances as artificial partheno- 

 genesis ; to Weindl's chemical proof of the presence of the antecedents 

 of future pigment in the transparent eggs of the squid ; to Hadzi's 

 observation on Hydra viridis that eggs laid in the dark developed into 

 white polyps, since the symbiotic Algas, which usually migrate from 

 mother to germ, do not migrate when there is no light stimulus ; to 

 the evidence of regenerative capacity in unexpected situations - in 

 Ophryotrocha, in the leech, in fresh-water snails, in Amphioxus, in the 

 limbs of the fresh-water spider and the praying mantis, in the lungs of 

 the salamander, in the jaw of lizards ; to Kammerer's argument that 

 artificially induced changes in the mode of reproduction may be trans- 

 mitted ; to the change in a hermit crab's abdomen when it is allowed 

 no shell to hide in ; and to many other interesting cases. 



Chemical Nature of Albinism.} — CI. P. Mudge has followed up 

 Cuenot's suggestion that albinos are colourless, because their skins lack 

 one of two factors, a chromogen or a ferment. Durham's results in- 

 dicate that the hair or skin of pigmented animals contains a ferment 

 (tyrosinase ?) which, acting on tyrosin, produces a pigment. The skin 

 of albinos, on the other hand, gives negative results. We may there- 

 fore tentatively infer that the albino lacks the ferment and carries the 

 chromogen. Mudge treated albino rats by immersion in a solution of 

 10 p.c. formalin and 70 p.c. spirit. In a short time the hairs became 

 vivid yellow. That this coloration is due to the presence of a specific 

 body, diffused through the keratin, and not to mere reaction between 

 the keratin and the formalin, is suggested by various observations. 



Races of Indian Rats.§ — R. E. Lloyd has made a careful study of 

 the races of Indian rats. He discusses the numerous single sports, the 



* G.R. Soc. Biol. Paris, lxvi. (1909) pp. 747-9. 



t Verh Zool. Bot. Ges. Wien, lviii. (190S) pp. 170-80. 



% Proc. Physiol. Soc. Joum. Physiol., xxxviii. (March 27, 1909) pp. 1-2. 



§ Records Indian Museum, iii. (1909) pp. 1-100 (7 pis.). 



