Anahotism and Specialisation. 209 



with slightly different tendencies to variation, where the 

 divergent blend of this kind becomes most essential, it even 

 seems that nature may have selected forms along two lines, 

 so as to produce the greatest divergence possible between the 

 sexes in their tendency to the two different types of anabolism. 

 By this means a forward evolution would be compatible with 

 the greatest retention of potential, or, taking animals as an 

 example, the greatest variation coupled with the greatest 

 stability in the products of anabolism, and in plants, the 

 greatest variation coupled with the greatest instability in the 

 products of anabolism. It perhaps should be pointed out that 

 variation in plants would depend upon divergence in the type 

 of stability of anabolism, in animals, along lines of instability 

 of anabolism. Variation in plants being associated with and 

 perhaps more or less due to the form of anabolism peculiar to 

 plants, and that in animals being associated with, and perhaps 

 more or less due to the peculiar form of anabolism found in 

 animals, it follows that variation is more likely to occur in 

 that form of germ cell which shows the peculiar kind of 

 anabolism most evidently. The source of variation would 

 chiefly lie in the more specialised germ cell, whether male or 

 female, but not necessarily limited to this cell. This would 

 usually be the sperm cell in animals, as the tendency to vary 

 on the part of the female germ would be more or less hindered 

 by its more stable form of anabolism. On the other hand, 

 this tendency on the part of the female germ would offer 

 greater possibilities of variation in the direction of the plant 

 type of specialisation for natural selection to work on. 



Turning next to the factors tending to a return along the 

 path of evolution, which would be along the lines of in- 

 creasing stability in animals and increasing instability in 

 plants, I am aware that the idea that there is any rekindling 

 of life, if we may so call it, brought about by conjugation 

 and free crossing, is entirely rejected by some authorities on 

 the subject. Others, however, do admit the possibility of 

 such a return, and for these it is hardly necessary to refer to 

 the evidence which leads to this belief, and which appears 

 to be so thoroughly established by the great powers of cell 

 division induced by these processes, and the extent to which 



