264 Theories Treating of Inheritance 



individual point a different cell substance as the pre- 

 dominant element. Then if the egg contains the sub- 

 stance characteristic of certain cells of the organism, 

 it must be affected at the same time as these cells and 

 by the same influences. According as these influences 

 exert an exciting or depressing influence and so provoke 

 the corresponding organ to further development or to 

 atrophy, there will be produced a similar action in the 

 egg, the corresponding substances will undergo a certain 

 growth or a certain regression and when the egg develops, 

 the cells whose task it is to localize these substances 

 within them, will experience the effects of this regression 

 or of this growth." 198 



In the first place it is to be noted here that the organs 

 whose modifications produce new phyletic stages do not 

 usually either develop or atrophy uniformly in all direc- 

 tions. Indeed, specific morphological alteration consists 

 rather in a growth or diminution always proportionally 

 unlike in different directions. The particular substance 

 which has increased in the egg can serve at most for 

 the explanation of a quantitative increase in mass of the 

 organ, but not for a morphological increase, different in 

 each different direction, like that which the parent organ- 

 ism has experienced. 



In the second place this explanation cannot be satis- 

 factory since there may be growth in one organ, while 

 another organ consisting of the same tissue, such as 

 nervous, muscular, bony tissue, etc., may remain un- 

 changed or even regress. These organs consisting of 

 the same tissue ought all to grow or diminish alike with 



198 Delage : Ibid. P. 837. 



