NON-MATHEMATICAL SCIENCES 189 



of heredity. Even such a phenomenon might 

 possibly be reconciled with Mendel's law when 

 we consider that natural selection must be 

 operating even among the reproductive cells 

 themselves, of which "many are called but few 

 are chosen." Yet it seems likely that further 

 investigation will show some departure from the 

 general law that chance alone determines he- 

 redity. 



Yet if the wish of biology is to resemble phys- 

 ics and chemistry, that wish is fulfilled, for we 

 have seen how each law of the physical sciences 

 has in course of time been supplanted by a more 

 general or a more accurate law — a process 

 which we may expect to see continued as long 

 as science itself continues. So Mendel's law, and 

 the body of biological knowledge which has fol- 

 lowed in its train, represent a great first ap- 

 proximation to the understanding of heredity, 

 which, in its turn, w^ill be followed by second and 

 third approximations as we travel onward 

 toward the receding horizon of scientific truth. 



