4. All the evidence we have in favor of the fixedness of species is, of course, evidence not only against Darwinism, but against evolution in all its forms. It would seem idle to discuss the question of the mutability of species, until satisfied what species is. This, unhappily, is a question which it is exceedingly difficult to answer. Not only do the definitions given by scientific men differ almost indefinitely, but there is endless diversity in classification. Think of four hundred and eighty species of humming-birds. Haeckel says that one naturalist makes ten, another forty, another two hundred, and another one, species of a certain fossil; and we have just heard that Agassiz had collected eight hundred species of the same fossil animal. Haeckel also says (p. 246), that there are no two zooelogists or any two botanists who agree altogether in their classification. Mr. Darwin says, "No clear line of demarcation has yet been drawn between species and sub-species, and varieties." (p. 61) It is absolutely necessary, therefore, that a distinction should be made between artificial and natural species. No man asserts the immutability of all those varieties of plants and animals, which naturalists, for the convenience of classification, may call distinct species. Haeckel, for example, gives a list of twelve species of man. So any one may make fifty species of dogs, or of horses. This is a mere artificial distinction, which amounts to nothing. There is far greater difference between a pouter and a carrier pigeon, than between a Caucasian and a Mongolian. To call the former varieties of the same species, and the latter distinct species, is altogether arbitrary. Nevertheless, notwithstanding the arbitrary classifications of naturalists, it remains true that there are what Professor Dana calls "units" of the organic world. "When individuals multiply from generation to generation, it is but a repetition of the primordial type-idea, and the true notion of the species is not in the resulting group, but in the idea or potential element which is the basis of every individual of the group."[50] Dr. Morton's definition of species as "primordial organic forms," agrees with that given by Professor Dana; and both agree with the Bible, which says that God created plants and animals each after its kind. A primordial form is a form which was not evolved out of some other form, but which began to be in the form--subject to such varieties as we see in the dog, horse, and man--in which it continued during the whole period of its existence.