98 



THE EVOLUTION OF SEX. 



cell-substance, consisting in part of genuine living matter or 

 protoplasm ; and there is the nucleus, or " germinal vesicle," 

 which plays such an important part in the ripening, fertilising, 

 and subsequent division of the cell. 



The cell-substance exhibits, when highly magnified, a homo- 

 geneous matrix, traversed by a delicate network, with minute 

 yolk-balls, pigment, and other granules strewn about the meshes. 

 So much of it is genuine protoplasm, of course, but then there 

 are also substances in process of ascent and even descent from 

 the climax of living matter, and there is in more or less abund- 



Ovum of a Threadworm (Ascar/s), showing (a) the 

 chromatin elements of the nucleus, and the appear- 

 ance of the surrounding yolk. — From Carnoy. 



ance a reserve capital of yolk nutriment for the future embryo. 

 Delicate observations, by the modern masters of microscopic 

 technique, have detected many marvels in the egg-cell, into 

 which which we cannot at present enter. Thus, within the last 

 year, Boveri has drawn attention to a special element in the pro- 

 toplasm, which he calls arc/io/>/asm, a substance which, as its 

 name suggests, seems to have an altogether marvellous architec- 

 tural function in relation to the changes of the nucleus in 

 segmentation. 



