NOTES. 



Note 1 (p. 49). 



I HAVE been careful to speak of the " appearance " 

 of cyclical evolution presented by living things ; for, 

 on critical examination, it will be found that the 

 course of vegetable and of animal life is not exactly 

 represented by the figure of a cycle which returns 

 into itself. What actually happens, in all but the 

 lowest organisms, is that one part of the growing 

 germ {A) gives rise to tissues and organs; while 

 another part {B) remains in its primitive condition, 

 or is but slightly modified. The moiety A becomes 

 the body of the adult and, sooner or later, perishes, 

 while portions of the moiety B are detached and, as 

 offspring, continue the life of the species. Thus, if 

 we trace back an organism along the direct line of 

 descent from its remotest ancestor, B, as a whole, 

 has never suffered death; portions of it, only, have 

 been cast off and died in each individual offspring. 



Everybody is familiar with the way in which the 

 " suckers " of a strawberry plant behave. A thin 

 cylinder of living tissue keeps on growing at its 

 free end, until it attains a considerable length. At 



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