2 LEBRUN. 



The ovary of Diemyctilus contains from five to six species of 

 eggs in different stages of development. I will not attempt to 

 detail the history of these eggs from ovogony to the maturation 

 stage, but will only state that, as a result of my investigations, I 

 have found absolute confirmation of my researches on European 

 urodels and on Siredon. 



I will here limit my references to the process of the maturation 

 of the egg. 



When the egg is ripe, the nucleus is situated at the animal pole, 

 voluminous, and contains four to five hundred chromatic nucleoles, 

 in various stages of dissolution, and resolving into granula. The 

 first appearance of maturation is the vacuolization of the karyo- 

 plasma and the dissolution of all the granular chromatin, except 

 a little quantity of nucleoles. These have in this stage a pro- 

 pensity to fuse together. Shortly, the membrane of the nucleus 

 disappears, and during this stage, the chromatic element is repre- 

 sented in the egg by spherical nucleoles and by masses made by 

 fusion of other nucleoles. 



All these phenomena are finished in the ovaries. When 

 the egg is found in the peritoneum the spindle of the first 

 polar body is finished and the chromosomes fixed on the spindle. 

 These are formed in a small region of karyoplasma which is not 

 invaded by the cytoplasmic inclusions after the disappearance of 

 the nuclear membrane. There are no centrosomes, but beauti- 

 ful asters. The filaments of these orders are crossed on the 

 equatorial plane of the figure as is known, by Batraclwceps 

 (Eisen), by pollen-mutter cells (Osterhout and his pupils) and 

 tritons (Lebrun). The first figure and the expelling of the first 

 polar body is finished in the superior part of the oviduct. The 

 second figure runs out during the egg's passage through the 

 oviduct to the cloaca. The chromosomes are twelve as in the 

 other urodels. They are quadripartite as in the first polar fig- 

 ure and have the form of a cross, resembling those found in 

 European tritons and called " oiselets." I will not, by this, say 

 that I give to these forms the same signification as do Von Rath, 

 Haecker, and others. On the contrary, I conclude that in the 

 two figures the chromosomes divide longitudinally in the equa- 

 torial plane. 



SAN FRANCISCO, CAL. , May 15, 1901. 



