Origin of Different Kinds of Adaptations 371 
out discussion, and that in some cases the length of life and 
the coming to maturity of the germ-cell may be, in some way, 
physiologically connected seems not improbable ; but that this 
relation has been regulated by the competition of species 
with each other can scarcely be seriously maintained. I will 
not pretend to say whether the mutation theory can or can- 
not be made to appear to give the semblance of an explana- 
tion of the length of life in each species, but it seems to me 
fairly certain that this is one of the questions which we are 
not yet in a position to attempt to consider on any theory of 
evolution. 
OrGANS OF EXTREME PERFECTION 
It has often been pointed out that certain organs may be 
more perfectly developed than the requirements of the sur- 
roundings strictly demand. At least we have no good reasons 
to suppose in some cases that constant selection is keeping 
certain organs at the highest possible point of development, 
yet, on the Darwinian theory, as soon as selection ceases 
to be operative the level of perfection must sink to that 
which the exigencies of the situation demand. The prob- 
lem may be expressed in a different way. Does the animal 
or plant ever possess organs that are more perfectly adapted 
than the absolute requirements demand? If such organs 
are the result of fluctuating variations, they will be unable 
to maintain themselves in subsequent generations without 
a constant process of selection going on. If, on the other 
hand, the organs have arisen as mutations, they may be- 
come permanently established without respect to the degree 
of perfection of their adaptation. We can see, therefore, 
that cases of extreme perfection meet with no difficulty on 
the mutation theory, while they have proven one of the 
stumbling-blocks to the selection theory. 
There are, in fact, many structures in the animal and plant 
kingdoms that appear to be more perfect than the require- 
