DENDEOCOMETES PARADOXUS. 345 



part of tliis modified chromatin is arranged in the form of 

 a thick ring at the periphery. There are^ however, some 

 strands stretching across the nucleus, and a considerable 

 number of rows of granules extending from the edge into the 

 cytoplasm. I think there can be little doubt that at this stage 

 either the whole or the greater part of the chromatin, in its 

 modified form, passes into the surrounding cytoplasm, leaving 

 the new meganucleus perfectly clear and homogeneous. 



The elimination of chromatin from nuclei is a phenomenon 

 of rare occurrence in animal and vegetable cells. In the 

 maturation of the ovum of many animals a considerable 

 amount of chromatin is ejected into the cytoplasm. Wilson 

 (26) says, " In these cases (Asterias, Polychserus, Thalassema, 

 Nereis) only a small fraction of the chromatin substance is 

 preserved to form the chromosomes, the remainder degene- 

 rating in the cytoplasm. Some years ago I described the 

 fragmentation of the germinal vesicle of the Stylasterid 

 AUopora (this Journal, vol. xxix) and the distribution of 

 its chromatin in the cytoplasm. A similar phenomenon 

 occurs in Distichopora (10). I have recently devoted a 

 considerable amount of attention to the ovutn of Alcyonium, 

 and in this case, too, the whole of the chromatin appears to 

 be ejected into the cytoplasm before fertilisation takes place. 

 In certain insects, judging from the figures given by 

 Henkiiig (9) and others, the amount of chromatin that 

 takes part in the formation of the first polar figure is a 

 very suiall fraction of the chromatin originally present in 

 the germinal vesicle (cf. Cuenot, 3a). 



That the elimination of chromatin is not confined to the 

 nuclei of egg cells is clear from the discovery of Boveri's, 

 that in those blastomeres in the early stages of development 

 of Ascaris which are destined to produce somatic cells, "a 

 portion of the chromatin is cast out into the cytoplasm, 

 where it degenerates, and only in the germ cells is the 

 sum total of the chromatin retained" (quoted from 

 Wilson, 26). In all these cases of the elimination of 

 chromatin from the nuclei of ova and blastomeres there 



