348 Evolution and Adaptation 
that in the egg of the snail. Zeleny has found a similar rela- 
tion to exist for the big and the little opercula of the marine 
worm, Hydroides. 
Let us consider now the more general questions involved 
in these symmetrical and asymmetrical relations between the 
organism and its environment. In what sense, it may be 
asked, is the symmetry of a form an adaptation to its environ- 
ment? That the kind of symmetry gives to the animal in many 
cases a certain advantage in relation to its environment is so 
evident that I think it will not be questioned. The main 
question is how this relation is supposed to have been attained. 
Three points of view suggest themselves: First, that the form 
has resulted directly from the action of the environment upon 
the organism. This is the Lamarckian point of view, which 
we rejected as improbable. Second, that the form has been 
slowly acquired by selecting those individual variations that 
best suited it to a given set of surrounding conditions. This 
is the Darwinian view, which we also reject. The third, 
that the origin of the form has had nothing to do with the 
environment, but appeared independently of it. Having, 
however, appeared, it has been able to perpetuate itself under 
certain conditions. , 
It should be pointed out that the Darwinian view does not 
suppose that the environment actually produces any of the new 
variations which it selects after they have appeared, but in so 
_ far as the environment selects individual differences it is sup- 
posed to determine the direction in which evolution takes 
place. On the theory that evolution has taken place indepen- 
dently of selection, this latter is not supposed to be the case; 
the finished products, so to speak, are offered to the environ- 
ment ; and if they pass muster, even ever so badly, they may 
continue to propagate themselves. 
The asymmetrical form of certain animals living in a sym- 
metrical environment might be used as an argument to 
show that the relation of symmetry between an animal and 
