172 Darwin and Embryology 
To what extent have the results of this vast activity fulfilled the 
expectations of the workers who have achieved them? The Darwin 
centenary is a fitting moment at which to take stock of our position. 
In this inquiry we shall leave out of consideration the immense and 
intensely interesting additions to our knowledge of Natural History. 
These may be said to constitute a capital fund upon which philo- 
sophers, poets and men of science will draw for many generations. 
The interest of Natural History existed long before Darwinian 
evolution was thought of and will endure without any reference to 
philosophic speculations. She is a mistress in whose face are beauties 
and in whose arms are delights elsewhere unattainable. She is and 
always has been pursued for her own sake without any reference to 
philosophy, science, or utility. 
Darwin’s own views of the bearing of the facts of embryology 
upon questions of wide scientific interest are perfectly clear. He 
writes?!: 
“On the other hand it is highly probable that with many animals 
the embryonic or larval stages show us, more or less completely, the 
condition of the progenitor of the whole group in its adult state. In 
the great class of the Crustacea, forms wonderfully distinct from each 
other, namely, suctorial parasites, cirripedes, entomostraca, and even 
the malacostraca, appear at first as larvae under the nauplius-form; 
and as these larvae live and feed in the open sea, and are not adapted 
for any peculiar habits of life, and from other reasons assigned by 
Fritz Miiller, it is probable that at some very remote period an 
independent adult animal, resembling the Nauplius, existed, and 
subsequently produced, along several divergent lines of descent, the 
above-named great Crustacean groups. So again it is probable, 
from what we know of the embryos of mammals, birds, fishes, and 
reptiles, that these animals are the modified descendants of some 
ancient progenitor, which was furnished in its adult state with 
branchiae, a swim-bladder, four fin-like limbs, and a long tail, all 
fitted for an aquatic life. 
“As all the organic beings, extinct and recent, which have ever 
lived, can be arranged within a few great classes; and as all within 
each class have, according to our theory, been connected together by 
fine gradations, the best, and, if our collections were nearly perfect, 
the only possible arrangement, would be genealogical; descent being 
the hidden bond of connexion which naturalists have been seeking 
under the term of the Natural System. On this view we can under- 
stand how it is that, in the eyes of most naturalists, the structure of 
the embryo is even more important for classification than that of the 
adult. In two or more groups of animals, however much they may 
1 Origin (6th edit.), p. 395. 
