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THE AMERICAN NATURALIST. [Vol. XXXIX. 



fuse into one. The nucleoli unite and so thoroughly does the 

 paternal and maternal chromatin seem to be mixed in the resting 

 condition that the fertiUzed &gg nucleus can scarcely be distin- 

 guished from the unfertilized. There would seem to be then a 

 fusion nucleus in the lily with the chromatin in the resting 

 condition. The figures and brief accounts of other botanists 

 indicate that similar conditions may be expected in other angio- 

 sperms. But no one has followed the chromatin in the fusion 

 nucleus through its later history, during the organization of the 

 chromosomes preparatory to the first mitosis following fertiliza- 

 tion. It would be very surprising if paternal and maternal 

 chromatin did not remain entirely independent of each other 

 as in the pine. The detailed study of fertilization in the angio- 

 sperms presents a very attractive subject for investigation. 

 Some very interesting conditions of fertilization have been 



Fig. i8. — Fertilization in Otwclea sensibUis. a, sperm as a spiral band within the egg nu- 

 cleus ; 3, later stage, the chromatin of the sperm much less condensed and more widely 

 distributed in the egg nucleus (after Shaw, '^Sa). 



described in the pteridophytes for Onoclea by Shaw ('98 a), 

 confirmed by Mottier {:04 a; :04 b), and for Adiantum and 

 Aspidium by Thorn ('99). In these forms the male nucleus 

 after leaving in the protoplasm of the egg all of the cytoplasmic 

 structures of the sperm (blepharoplasts, cilia, etc.) enters the 

 egg nucleus as a more or less spiral body which stains deeply 

 and is evidently chiefly or wholly chromatic in composition (Fig. 

 18). Within the egg the dense structure of the sperm nucleus 

 becomes looser by the .separation of the chromatin granules (Fig. 



