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.” 798 
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 
*Delage: Ibid. P. 837. 
