It is only, in fact, by surrendering the principle that similarity entails community of origin, and by falling back on the suggested common basis of general laws, that Transformism makes room in its system for the troublesome facts of convergence. “It might be reiterated in passing,” says Dwight, “that this ‘convergence’ business is a very ticklish one. We have been taught almost word for word that resemblance implies relationship, or almost predicates it; but according to this doctrine it has nothing to do with it whatever.” (“Thoughts of a Cath. Anat.,” p. 190.) And in a subsequent chapter he says: “No very deep knowledge of comparative anatomy is needed for us to know that very similar adaptations for particular purposes are found in very diverse animals. The curious low grade mammal, the _Ornithorhynchus_, with a hairy coat and the bill of a duck, is a familiar instance. We all know that the whales have the general form of the fish, although they are mammals, and going more into details we know that the whale’s flipper is on the same general plan as that of the ancient saurians.... The origin of the eye, according to evolutionary doctrines, has been a very difficult problem, which gets worse rather than better the more you do for it. Even if we could persuade ourselves that certain cells blundered along by the lucky mating of individuals in whom they were a bit better developed than in the others till they came to form a most complicated organ of sight, it would be a sufficient tax on our credulity to believe that this could come off successfully in some extraordinary lucky species; but that it should have turned out so well with all kinds of vertebrates is really too much to ask us to swallow. But this is not all: eyes are very widely spread among different classes of invertebrates. More wonderful still, the eyes of certain molluscs and crustacea are on stalks, and this is found also in various and very different families of fishes. How did this happen? Was it by way of descent from the molluscs or the crustacea? If not, how could chance have brought about such a similar result in diverse forms?” (_Op. cit._, pp. 233-236.)