90 



INDIVIDUALITY IN ORGANISMS 



when a certain size or length is 

 attained, or the appearance of 

 buds at a certain distance from 

 the chief growing tip in plants, are 

 cases in point. In many cases 

 experimental control and alteration 

 of these relations throws a flood of 

 Hght upon the problem of their 

 nature. It is with material and 

 experiments of this sort that the 

 present chapter is largely 

 concerned. 



I have shown elsewhere that 

 the process of progressive develop- 

 ment and differentiation in the 

 individual is accompanied by a 

 decrease in the metabohc rate 

 determined by the accumulation 

 of relatively inactive constituents 

 in the protoplasm. These changes, 

 which constitute 

 senescence, may 

 "^ eud in death if 

 they go far enough. 

 On the other hand, 

 any change which 

 brings about the 

 removal of such 

 previously accu- 

 mulated material 

 makes possible an 

 acceleration in metabolic rate, and such changes con- 



FiGS. 42, 43. — Tuhularia: Fig. 42, a single 

 individual; Fig. 43, asexual reproduction 

 from tip of stolon. 



