ZOOLOaY AND BOTANY, MICROSCOPY, ETC. 493 



the broad zone at tlie wide end of the egg, or the latter itself, which is 

 chiefly affected by the colouring of oorhodein. Leuckhart in 1853 

 expressed the opinion that the colours which, according to the obser- 

 vations of Carus, are deposited on the shell in the oviduct, appear to 

 be of two kinds. The one which gives a uniform appearance to the 

 whole surface of the shell, originates apparently in certain specific pig- 

 ments which combine with the separated lime ; the other, which 

 commonly appears in spots or in ramifying lines, originates from a 

 more or less changed colouring matter of blood, which makes its way 

 through the swollen vessels of the oviduct, and imprints itself on the 

 egg. In the first case it is the green colour, in the others the red, 

 with its manifold shades, which predominate over all others. 



It appears, from the chemical and physical properties of the pig- 

 ments, that there is a closer chemical relation between oorhodein and 

 haemoglobin than between the latter and oocyan. 



Presence of Glycogen in Embryos of Squalidse.* — E. Blanchard 

 has found that in embryos of Mustelus vulgaris, 8J cm. long, 

 the yolk-sac is covered by a number of blood-vessels. On its 

 internal surface there is a flattened epithelium, the cells of which, 

 provided with a large nucleus, contain a certain number of large 

 refractive granulations which are blackened by osmic acid. Some of 

 these cells distinctly give the glycogen-reaction, but the same reaction 

 is not to be obtained at any other point of the yolk-sac, nor in the 

 umbilical cord. 



The author points out that, in mammals, the placenta is the seat 

 of the formation of glycogen during the earlier stages of foetal exist- 

 ence, and that, inasmuch as the membrane of the yolk-sac of vivi- 

 parous Squalidse plays the same part as the placenta, we may extend 

 the statement as to the existence of glycogen from mammals to these 

 fishes. 



Biological Studies.f — ^H. Eisig placed in a basin of water an 

 Octopus, a Gohius, and a Pagurus with an Actinian on its shell ; the 

 Octopus attacked the crab, which immediately withdrew into its shell, 

 while the attacker instantly retreated, for the stinging organs of the 

 Actinia had been too much for it. The same thing happened with 

 the goby. A Pagurus without a shell was afterwards placed near 

 the Octopus, and the latter examined it very carefully before it dared 

 to seize it. At the same time it is to be observed that the Actinian 

 gets much assistance from its commensal, thanks to the locomotive 

 and olfactory powers of the latter. 



Observations on thermal conditions showed that many fishes 

 and other marine forms were but little affected by alterations in 

 temperature ; while a study of the modes of resting of marine forms 

 shows that much depends on what region of the sea the subjects 

 naturally inhabit, and considerable differences are to be observed be- 

 tween pelagic and more deeply dwelling fishes and cephalopods. 



* Bull. Soc. Zool. France, vii. (1883) p. 405. 

 t Biol. Centralbl., iii. (1883) pp. 142-4. 



