CHAPTER SEVEN. 
Heredity. 
The subject of heredity is intimately bound up with 
the evolutionary hypothesis and, it must be admitted, cre- 
ates a new difficulty for the acceptance of the theory. 
Indeed, the laws of heredity, so far as understood, ap- 
pear to contradict the theory of Lamarck and Darwin at 
a vital point, if not at the vital point of the entire structure 
raised in-the “Origin of Species.” It is necessary in 
order to appreciate the strength of this objection, to re- 
call once more the outstanding features of the hypothesis 
by which scientists have attempted to account for the 
variety of living forms. The various theories of organic 
evolution, whether Lamarckian, neo-Lamarckian, or Dar- 
winian, are based upon the assumption that animals and 
plants have a tendency to perpetuate by transmission to 
offspring a variation which has proven useful as an aid 
to the particular species in its struggle for existence. 
We have just discussed, in the chapters on the Fixity of 
Species and on Rudimentary Organs, certain difficulties 
which loom up when the question is raised, How did 
varieties become distinct species? However, even if it 
were to be assumed that some satisfying answer might 
be found to this question so far as the stages of incom- 
plete organs are concerned, there is one fact in heredity 
which, it would seem to me, strikes at the very heart of 
the theory. 
In his “Philosophic Zoologique” (1809), Lamarck first 
explicitly formulated his ideas as to the transmutation 
