PLANT-LIFE ASSIMILATION. 225 



ant members as it waxes into its full norm. 

 Noteworthy is the fact that the Plant has the 

 tendency to reproduce the organs of which 

 it has been deprived, wherein it is quite dif- 

 ferent from the animal, at least the higher 

 ones. Bootless stems will send out new 

 roots, and stemless roots will put forth stern 

 and leaf. This indicates the lower organiza- 

 tion of the Plant, of which each part is able 

 to be the process of the whole, not being dif- 

 ferentiated too deeply from the same. There 

 is likewise in Plant-life a periodicity of many 

 kinds, in part externally dependent upon day 

 and night, the cycle of the seasons, tempera- 

 ture, etc. But Plant-life has its inner period- 

 icity of birth, maturity and cessation lasting 

 a few hours in some Algae and many hund- 

 reds, perhaps thousands of years in some 

 trees. Here again the vegetal individual as- 

 similates itself to the norm of the duration 

 of its species. But whence comes this species 

 which seems to mould each plant after its 

 foreordained type? On this question a large 

 amount of recent biology has turned. 



Through growth the Plant reveals its pro- 

 pulsion to attain the universal form of its 

 kind, to be one with its genetic source; this 

 is its supreme Assimilation. But it remains 

 a striving externally directed; the concentric 

 layers of the oak, yearly added one after the 



