310 Explanation of Inheritance 
centroepigenesis is able to account for the inheritance of 
acquired characters in general, the particular case of this 
inheritance, constituted by sexual dimorphism and by 
polymorphism in general, which up till now we have 
been compelled to leave aside, becomes explained at once. 
The question of primary and secondary sexual char- 
acters, writes Delage, is connected with one of the most 
important questions of general biology: “When one 
part develops in a certain way another part develops 
correlatively in a certain way, and if the first had devel- 
oped in another way, the development of the second 
would also have been different; and this although no 
direct connection exists between these two parts. The 
question presents itself also in the following way: In 
what way and under what form can this reciprocal 
influence of the organs acting at a distance be effected 
without any similarity between cause and effect?” 22° 
The explanation which the centroepigenetic hypothesis 
can afford for sexual dimorphism is the following: It is 
due to the fact that in the whole series of germinal specific 
potential elements there are found interpolated two dis- 
tinct groups of these elements, such that the activation 
by the central zone of one of these groups would pre- 
clude the activation of the other and vice versa. Then as 
soon as the two sexes have commenced to differ somat- 
ically even a very little from each other, every later 
sexual character, whether principal or secondary, acquired 
by functional adaptation by the male or female, or better 
the entire conformation of the whole organism resulting 
therefrom, would become represented in the central zone 
of that organism by a corresponding small group of 
*°Delage: L’hérédité etc. P. 184—185. 
