VOYAGE FROM NEW YORK TO RIO DE JANEIRO. 41 
ence, and are not yet very extensively known in the com- 
munity ; but when the facts are more fully understood, they 
cannot fail to affect the fundamental principles of zoology. 
I have been astonished to see how little weight Darwin 
himself gives to this series of transformations ; he hardly 
alludes to it, and yet it has a very direct bearing on his 
theory, since it shows that, however great the divergence 
from the starting-point in any process of development, it 
ever returns to the road of its normal destiny ; the cycle 
may be wide, but the boundaries are as impassable as if it 
were narrower. However these processes of development 
may approach, or even cross each other, they never end in 
making any living being different from the one which gave 
it birth, though in reaching that point it may pass through 
phases resembling other animals. 
" In considering these questions we should remember how 
slight are most of those specific differences, the origin of 
which gives rise to so much controversy, in comparison with 
the cycle of changes undergone by every individual in the 
course of its development. There are numerous genera, 
including many very closely allied species, distinguished by 
differences which, were it not for the fact that they have 
remained unchanged and invariable through ages, might be 
termed insignificant. Such, for instance, are the various 
species of corals found in the everglades of Florida, where 
they lived and died ages ago, and had the identical 
bpecific differences by which we distinguish their succes- 
sors in the present Florida reefs. The whole science of 
zoology in its present condition is based upon the fact that 
these slight differences are maintained generation after gen- 
eration. And yet every individual on such a coral stock, 
and the same is true of any individual in any < lass whatso- 
