THE IDEA OF GERMINAL CONTINUITY 43 



of the hereditary qualities. In development a part of the germ- 

 plasm, " contained in the parent egg-cell, is not used up in the 

 construction of the body of the offspring, but is reserved un- 

 changed for the formation of the germ-cells of the following 

 generation." Thus the parent is rather the trustee of the 

 germ-plasm than the producer of the child. In a new 

 sense, the child is " a chip of the old block," As Sir Michael 

 Foster put it, " The animal body is in reality a vehicle for 

 ova ; and after the life of the parent has become potentially 



Fig. 9. — Diagram illustrating idea of germinal continuity. 

 (After E. B. Wilson.) 



G', fertilised ovum dividing into lineage of body-cells (B) and lineage of germ-cells — the 

 base line ; B', B", the bodies of two successive generations ; G', G% G', G^, G', the chain 

 of germ-cells. 



renewed in the offspring, the body remains as a cast-off 

 envelope whose future is but to die." To use another 

 metaphor, the germ-plasm is the lighted torch handed on 

 from one runner to another. " Et quasi cursores vitai lampada 

 tradunt." 



Early segregation of the germ-cells is in many cases an oh- 

 servable fact — and doubtless the list of such cases will be added 

 to ; but the conception of a germ-plasm is hypothetical, just as 

 the conception of a specific living stuff or protoplasm is hypo- 

 thetical In the complex microcosm of the cell we cannot point 

 to any one stuff and say, " This is protoplasm " ; it may well be 



