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, according 

 to Boveri, this 

 splitting off or 

 isolation of the 

 germplasm occurs 

 as early in the 

 cleavage of the 

 fertilized egg as 

 the sixteen -cell 

 stage, when fifteen 

 of the cells go to 

 form the somato- 

 plasm and the 

 sixteenth is set 

 aside as germ- 

 plasm. 



Thus there re- 

 sults a continuous stream of germplasm, receiving 

 contributions from other germplasmal streams at the 



SONfATOPLASM 



Fio. 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. 



