60 Journal of the Mitchell Society [December 



realizations) are co-dependent, all varying, or rather having varied in 

 the same direction. They are, as Hentschel says, "functions of one 

 another or of the same variable," the latter an environmental factor. 

 We must of course suppose, since presumably we are dealing with 

 germinal and not with somatogenic characters, that the environmental 

 (external or internal) factor, as it increases in force, continues to modi- 

 fy the germ in the same detail of its constitution (same gene or gene 

 complex) and in the same direction. This brings us well into the field 

 of speculation, but without speculation no rational experimentation. 

 Chapel Hill, N. C. 



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