PRESIDENTIAL ADDRESS. 39 



ter of similar cells, but these units soon lost their original 

 homogeneity. As the result of mere relative position, some of 

 the cells were especially fitted to provide for the nutrition of 

 the colony, while others undertook the work of reproduction. 

 Hence the single group would come to be divided into two 

 groups of cells, which may be called somatic and reproductive 

 the cells of the body as opposed to those which are concerned 

 with reproduction (p. 27) ... As the complexity of the 

 metazoan body increased, the two groups of cells became more 

 sharply separated from each other. Very soon the somatic 

 cells surpassed the reproductive in number, and during the in 

 crease they became more and more broken up by the principle 

 of the division of labor into sharply separated systems of tis 

 sues. As these changes took place the power of reproducing 

 large parts of the organism was lost, while the power of repro 

 ducing the whole individual became concentrated in the repro 

 ductive cells alone " (p. 28). His theory further assumes that 

 the germ-cells contain two kinds of plasm, which he calls re 

 spectively the ovogenetic and the somatogenic, i. e., the first 

 capable only of producing germ-cells, the latter capable only 

 of producing somatic cells. These exist together in the fertil 

 ized ovum, and if allowed to remain there would go on repro 

 ducing themselves in something like equal numbers. But the 

 body consisting almost entirely of somatic cells, it is evident 

 that such a multiplication of germ-cells would be only a hin 

 drance to development. This, he claims, explains the myste 

 rious phenomena so long observed by embryologists and called 

 the removal of polar bodies. The polar body first removed is 

 nothing more nor less than the ovogenetic nucleo-plasm, which 

 is now in the way, and whose removal is necessary to the 

 formation of the embryo. This is the work alone of the somatic 

 cells, and these, consisting as they do of the germ-plasms of an 



