ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 285 



marked increase in the volume of the corium, involving the connective 

 tissue and both kinds of glands. Fourthly, the author describes a 

 peculiar, coffee-brown structure between skin and fascia in the region 

 of the last eight lumbar vetebras in Gervus elaphus, G. canadensis, G. 

 axis, and Gariacus campestris. It consists of a connective-tissue reti- 

 culum with many blood-vessels, isolated nerves, and large round cells 

 in the meshes. It recalls the glandula coccygea or the glandula 

 carotica. 



Optic Chiasma of Reptiles.* — J. Gross has studied the chiasma 

 nervorum opticorum in various reptiles, as a contribution to the dis- 

 cussion of a problem which has been the subject of controversy since 

 -the time of Galen . In the slow- worm, the gecko, Lacerta, and two 

 snakes, it seems clear that the crossing is total ; in Chelonians and the 

 •chamaeleon the case is not so clear, but it seems most probable that in 

 these as in other cases the crossing is total not partial. The histological 

 details are described in the different cases, which show remarkable 

 diversity. A very simple mode of crossing was probably primitive in 

 Reptilia, and Anguis fragilis is nearest the original simplicity. It is 

 interesting to notice how this research corroborates from the study of 

 the details of the chiasma conclusions which have been otherwise reached 

 in regard to the phylogenetic relationships of reptiles. 



General. 



Biogen-Hypothesis.t — Max Verworn states as a working hypothesis 

 a new version of an old idea. Metabolism depends on the continual 

 breaking-down and continual building-up of a very labile chemical 

 combination — the biogen-substance. This has its seat in the cytoplasm 

 >of the cell, rather than in the nucleus, which does not in itself show 

 respiratory changes. 



Note on Physiological Injections.:): — Yves Delage points out that 

 the method of injecting carminate of ammonia, indigo-carmine, and the 

 like, and observing where these substances are localised, is good so far 

 as it goes, but that it is apt to lead to fallacious conclusions. The sub- 

 stances in question are not products of normal excretion, and it does 

 not follow that the organs which excrete them after injection are 

 excretory in the normal metabolism, or that the organs which do not 

 excrete them may not be truly excretory. And to say that organs which 

 fix and accumulate the artificially introduced substances are excretory 

 at all, is like saying that the nervous system is excretory because it fixes 

 methylen-blue. 



Experiments with Adrenalin.§ — „Ch. Bouchard and H. Claude 

 remark on the remarkable properties of adrenalin as an agent inducing 

 vaso-constriction. They have made experiments (on rabbits) as to its 

 toxicity. The fatal dose of a solution injected into the veins is between 

 •1 and *2 mgrm. per kilogramme. In the intoxication there are 



* Zool. Jahrb., xvii. (1903) pp. 762-88 (2 pis.). 



t ' Die Biogenhypothese. Eine kritische-experimentelle Studie iiber die Vor- 

 giincrein der lebendigen Substanz,' Jena, 1903, 8vo, 114 pp. 



% Comptes Rendus, cxxxv. (1902) pp. 936-7. § Tom. cit., pp. 928-31. 



June 17th, 1903 U 



