HERITAGE OF THE INDIVIDUAL 



265 



follows that this must be the sole path of inheritance. In 

 other words, whatever characters the body actually inherits 

 must have been represented by genes in the fertilized egg 



Germplasm \ Somatoplasm 



FIG. 135. Scheme to illustrate the continuity of the germplasm. Each 

 triangle represents an individual composed of qermplasm (dotted) and somato- 

 plasm (clear). The beginning of the life cycle of each individual is at the 

 apex of the triangle where both germplasm and somatoplasm are present. In 

 biparental (sexual) reproduction the germplasms of two individuals become 

 associated in a common stream which is the germplasm and gives rise to the 

 somatoplasm of the new generation. This continuity is indicated by the heavy 

 broken line and the collateral contributions at each succeeding generation by 

 light broken lines. (From Walter.) 



from which it has arisen: and conversely, any characters 

 which the individual can transmit must be represented in 

 its germ cells. (Figs. 115, 135.) 



1 . Modifications 



Every individual organism a man, for instance is a 

 mosaic not only of inherited characters but also of MODIFICA- 

 TIONS of the soma produced by external conditions during 



