CLEAVAGE AND DIFFERENTIATION 



the cytoplasm, their conception of the action of the genes 

 as unalterably fixed entities can not explain differentiation 

 of development. For how could the genes be responsible 

 for differentiation, if they are the same in every cell?^ 

 Unless the geneticists assume that their genes are omnipo- 

 tent, we can not understand how the problem of differentia- 

 tion can be solved by the gene-theory of heredity.- 



The gene-theory of heredity is an ultra-mechanical rig- 

 orously bound concept. This mechanistic rigidity renders 

 it inadmissible as an explanation of the process of develop- 

 ment, a process marked by the egg's inherent capacity and 

 by its mobile responses to external influences. On the other 

 hand, the gene-theory, postulating factors in chromosomes, 

 fits in well with the stable and change-resisting character 

 of chromosomes. But in thus accentuating the relative 

 non-mutability of the chromosomes as carriers of heredity, 

 the most stable possession of the organism, the gene-theory 

 sets off the process of heredity from differentiation of 

 development; hence, as we have seen, it offers us no help 

 in our attempt to explain differentiation. 



Now the gene-theory as formulated may not be the only 

 way of interpreting the vast amount of reliable data accu- 

 mulated by the numerous geneticists the world over. 

 These many data, let us say at once, we accept. If, how- 

 ever, we can offer another interpretation of them, can for 

 example substitute for the factorial concept in the gene- 

 theory another concept which is less rigid, more consonant 

 with our knowledge of physiological processes and one 



^ Cf. Lillie, F. R., 192/; Conklin, 1924^ et. al. 



- Untutored savage man made his god as big as possible because 

 his god could do everything. It remained for the geneticists to 

 make one of molecular size, the gene. Here obviously infinite 

 minuteness means infinite capacity. According to one geneticist, 

 Demerec, the gene has almost magic power. This is physico- 

 chemical biology with a vengeance! 



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