ZOOLOGY AND BOTANY, MICROSCOPY. ETC. 211 



Spawning of Bufo vulgaris.* — M. Heron-Eoyer refers to 

 Van Bambeke's five layers which surround the egg of a Batrachian. 

 These are (1) the thin vitelline membrane ; (2) the chorion ; (3) the 

 internal transparent capsule ; (4) the external capsule ; and (5) the 

 thick, jelly-like envelope by means of which the eggs are fastened 

 together, and fixed to submerged objects. He then describes the 

 passage of the eggs through the oviduct, and the changes that take 

 place therein, their expulsion from the cloaca, and their fertilization 

 by the male. The attitude of the male during fertilization, and the 

 arrangement of the eggs in their envelopes in various Auura, are 

 figured. 



In Peldbates fusciis the eggs are scattered in the jelly without any 

 definite arrangement. P. cultripes rolls its string of eggs round 

 plants. In Bufo vulgaris the external and internal capsules form a 

 tube, inclosing a number of eggs in a common chamber. These two 

 layers are spherical in Ranidaj and Hylidas, as well as in Disco- 

 glossidae. They appear to be absent in Pelohates. In Axolutl two or 

 more eggs are laid in a common external capsule, each egg having its 

 own internal capsule ; the groups of eggs are placed end to end, and 

 surrounded by the jelly-like layer. During the development of the 

 embryo, these various layers, in all these forms, fuse with one 

 another. The author supposes that the external capsule of these 

 eggs is more apparent than real ; that the very short part played by 

 it is simply to prevent a mixture of the neighbouring layers; and 

 that its disajipearance precedes the free-swimming stage. 



Yolk-globules in the intracapsular fluid of Fish Ova.t — After 

 discussing the various opinions which have been held in regard to the 

 passage of water through the porous capsule of fish ova, Prof. B. 

 Solger maintains that the process occurs independent of fertilization, 

 before or after, or contemporaneously. 



By the entrance of water, the capsule in Leuciscus ova was seen 

 to be stretched and tense thirty hours after fertilization, and remained 

 so till, shortly before the liberation of the embryo, a large intracapsular 

 space was formed. In studying the contents of this space, Solger 

 found that the colourless internal fluid is at first (from the second to the 

 ninth day after fertilization) very readily affected by water, becoming 

 at once white and turbid, acting just like the yolk-substance of the 

 ovum. In examining the intracapsular fluid, formed elements were 

 discovered which closely resembled yolk-globules, though apparently 

 in process of breaking up. Precautions were of course taken to 

 prevent any injury to the wall of the yolk-sac. Professor Solger 

 points out the two possibilities — either the globules originate from 

 outside, just as His derives the yolk- globules themselves from the 

 granulosa, or, which seems to him the more probable, they originate 

 from the yolk before it is completely surrounded. He notes Elmer's 

 interesting observation that the further entrance of water is prevented 

 at a definite period by the development outside the porous capsule 



* Bull. Acad. K. Sci. Beige, x. (18S5) pp. 597-607 (1 pi.). 

 t Arch. f. Mikr. Anat., xxvi. (1885) pp. 321-33 (1 pi.). 



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