INTRODUCTION 



11 



of the individual, and this remains undifferentiated, 

 or in reserve, like a savings-bank account put by 

 for a rainy day, 

 while the somato- 

 plasm is expended 

 in the immediate 

 demands of the 

 tissues that make 

 up the individual. 

 In one instance at 

 least, that of the 

 nematode worm 

 Ascaris, as con- 

 firmed by Boveri, 

 this splitting off 

 or isolation of the 

 germplasm occurs 

 with the very first 

 cleavage of the 

 fertilized egg into 

 the two-celled 

 stage, when one 

 of the two cells 

 forms the future 

 germplasm, while 

 the other differen- 

 tiates by succes- 

 sive divisions into 

 the animal itself. 



Thus there results a continuous stream of germ- 

 plasm, receiving contributions from other germ- 



GE RMPLASM \ SO^ATOPLASM 



FIG. 2. Scheme to illustrate the continuity of 

 the germplasm. Each triangle represents an 

 individual made up of germplasm (dotted) and 

 somatoplasm (undotted) . The beginning of the 

 life cycle of each individual is represented at 

 the apex of the triangle where germplasm and 

 somatoplasm are both present. As the indi- 

 vidual develops each of these component parts 

 increases. In sexual reproduction the germ- 

 plasms of two individuals unite into a common 

 stream to which the somatoplasm makes no 

 contribution. The continuity of the germ- 

 plasm is shown by the heavy broken line into 

 which run collateral contributions from suc- 

 cessive sexual reproductions. 



