HEREDITY 89 



to perish, as did the vast array of bodies produced in the 

 past by our own particular streams of germ-plasm. The 

 germ-plasm alone endures, and may continue to endure 

 for an indefinite number of millions of years, giving off 

 further innumerable mortal bodies. 



This conception of the relations between germ-plasm 

 and body-plasm is well illustrated by the early develop- 

 ment of Cyclops. In Fig. 46, C, we see at each side of 

 the nucleus a number of radiating lines, the first appear- 

 ance of a sort of anchor in which the fibres which guide 

 the movements of the chromosomes will later be fixed 

 (Fig. 46, D). It is to be noticed that round about one 

 of these radiations are a number of dark granules, while 

 they are absent from the radiation at the opposite pole 

 of the nucleus. This results in one of the two cells formed 

 by the first division of the zygote possessing these granules, 

 while the other one is without them (Fig. 46, E, F). 



The next stage in development is that each of these 

 two cells with their contained nuclei divide into two, in 

 exactly the same way as before. The two cells derived 

 from the cell which lacks the granules will of course have 

 no granules. In the case of the other cell, the granules 

 behave as before, all congregating at the one pole of 

 the dividing nucleus, leaving the opposite pole free from 

 them. Division therefore results as before in one cell 

 with granules and the other without. Thus in the four 

 cell stage of the embryo we find three cells without 

 granules and one with them. For a time cell multipli- 

 cation proceeds in the same manner, all the descendants 

 of the cells without granules being free from them, while 

 the cell containing the granules always divides into one 

 cell with them and one without. The embryo thus 

 always has one cell, and only one, containing granules. 



