1892.] of the oosperm nucleus in certain ova. 15 



But how do these nuclei originate ? "By repeated division of 

 the first or oosperm nucleus " is the suggested answer to this 

 question ; but it is a curious and very suggestive fact that these 

 primary divisions of the oosperm nucleus have never been observed, 

 and further that the chromatin bodies of the undivided oosperm 

 nucleus, although it never returns to a true resting stage, are 

 remarkably small and numerous. 



No karyokinetic figures have been described in the earliest 

 stages of the development of birds. 



In Peripatus Novae Zealandise Miss Sheldon was unable to find 

 any very definite figures in the first nuclei that were formed, 

 although a large and typical spindle and spheres of attraction 

 have been described in the division of the oosperm nucleus of 

 Peripatus capensis. 



In Julus terrestris, according to Heathcote, the oosperm nucleus 

 divides into irregular lumps of considerable size, but no true karyo- 

 kinetic figures can be seen. 



In Insects we find some very conflicting evidence. 

 It is true that Henking has recently described and figured 

 some rather irregular karyokinetic figures in the first nuclear 

 divisions of the eggs of some insects that do not apparently 

 segment, but in Pieris, Pyrrochoris and Lasius he points out that 

 after the division of the first equatorial plate the chromosomes 

 disappear, and later — and this is the point to which I wish to call 

 particular attention — the chromosomes appear again and fuse 

 together to form larger bodies which exhibit an equatorial plate. 



It is noteworthy too that notwithstanding the fact that several 

 observers have carefully studied the development of the blowfly 

 (Musca), we have no very satisfactory account nor figure of the 

 karyokinetic division of the oosperm nucleus, notwithstanding the 

 fact that in later stages the karyokinetic figures are large, readily 

 seen and quite typical. 



Blochman, who figures the spindles of the naclear division to 

 form the polar bodies and also the spindles of the later stages of 

 the embryo, did not apparently observe the first division of the 

 oosperm nucleus. 



He says "Als erste Theilung des Eikernes kann man die Bilder 

 wohl nicht auffassen, weil, wie ein Blick auf die spateren Figuren 

 zeigt, bei Theilungen die Tochter kernplatten stets so fort weit aus 

 einander rlicken." 



Henking, who carefully investigated the early stages of the 

 blowfly, was unable to find the first division of the oosperm nucleus. 

 In his first paper he described the occurrence of free nuclear 

 formation in yolk. 



It does not seem at all reasonable to suppose that nuclei are 

 really formed in the substance of the egg cell from substances 



