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 1 : 



" 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. 



