THE EVOLUTION OF LIVING BEINGS. 6l 



tides can, under favorable conditions, interact in such 

 a way that life results. 



The conception of entirely independant hereditary 

 units, retaining their individuality unter all circum- 

 stances which by temporary linkage, like shuffled stic- 

 ky, differently colored, lumps of sugar, give rise to new 

 patterns, comparable to new species, reveals only the 

 naivite of those minds, who consider this a satisfactory 

 explanation of the very complicated interactions which 

 must take place in such a wonderful substance as two 

 fusing germ-plasma's 



What happens in the zygote is doubtless a very com- 

 plicated chemical, not a mere physical, process, as the 

 shuffling of different independant, hereditary units 

 would be. 



Yet, even so rough a scheme can be of service, and has 

 been of service, to assist us in gaining a first general in- 

 sight in what may happen, but when we forget the 

 initial inadequacy of this scheme, and especially when 

 we proceed to hide the inadequacey of the explanation, 

 by all kinds of suppositions, notwithstanding the 

 results of the crosses so , .explained" ought to have war- 

 ned us against believing in the adequacy of this expla- 

 nation, we get on very unsafe ground. So f. i. in those 

 cases, in which we are trying to explain the shortness of 

 hair, now by the loss of a factor, then again by the 

 addition of a factor, inhibiting the effect peculiar to a 

 length factor supposed to be present, we run great risk to 

 consider our duck a goose, and to gain unwarranted 

 confidence in a scheme which — at the most — can be, 

 but even need not be, correct in a very general way. 



