NA'TURE AND MAN 87 



far as these may effect the general health and nourishment 

 of the whole germ-cell or of some of its particles in a general 

 way. Variation comes about through the shuffling and deal- 

 ing of the granules in connection with the maturing and con- 

 jugation of the germ-cells. Its direction is not affected by en- 

 vironment or by habits and behavior of the parent. 



The variations which actually arise may be entirely unde- 

 termined^ perhaps in all directions equally. Of these radiat- 

 ing individuals natural selection allows some to live and kills 

 off the rest, and thus determines the direction of evolution 

 of the species. 



If the variation in such a series of generations is mostly 

 along one line or in only a few directions, it is guided more or 

 mostly by the tendencies of the germ-cells, and the work of 

 natural selection is correspondingly lightened. 



Says the neo-Lamarckian: ''The animal body is one and 

 control is one pervading the body and all its cells, even 

 germ-cells must be to some extent, at least, included under this 

 control. The germ-cells cannot have that independent and 

 exclusive autonomy postulated by the neo-Darwinian. 

 Bcdily variations cannot go on without producing correspond- 

 ing changes in the germ-cells, in some degree." How this 

 energy reaches the germ-cells is no clearer than how osteo- 

 blasts and osteoclasts are controlled, or how the arrangement 

 of cells in an embryo is brought about. The fact of control 

 is a different matter from the explanation of how it is brought 

 about. 



Both schools are beginning to see that each holds certain 

 points which the other would like to see fully proven; each 

 has its difficulties and hmitations. A compromise or higher 

 synthesis will probably replace both. Both agree that the di- 

 rection of the individual life experiment is determined very 

 largely by heredity, the energy inherent in the germ-cell. 

 Neither will deny that the final control of the grand strategy 

 of the evolution of life as a whole and its direction is in 

 large part the result of the process of natural selection. For 

 this in the end controls the survival and permanence of cer- 



