Haeckel takes this up, gives a resumé of the facts known to zoology on this point, and then winds up with the following: “In view of this state of affairs, we zoologists, recognized as authorities on the subject, may surely ask, How can many so-called anthropologists still maintain that there exists no sort of actual proofs of the ‘Derivation of Man from Apes’? How can Virchow, Ranke, and others, who are not zoologists, in the speeches they annually deliver at anthropological and other congresses, continue to declare that this ‘Pithecoid thesis’ is an empty hypothesis, an unproved assertion, and a mere dream of the philosophers of nature? How can these anthropologists still continue to ask for ‘certain proofs’ of this thesis when proofs with all the clearness that could be desired lie before them, and are unanimously recognized by all zoologists? As regards Virchow’s often quoted declarations against the Pithecoid thesis, they have obtained great favor in wide circles, only because of the high authority this famous naturalist enjoys in an entirely different domain of science. His ‘cellular pathology,’ his ingenious application of the cell-theory to the whole province of medicine, introduced a grand advance in that branch of science thirty years ago. This great and lasting service rendered by him has, however, no connection whatever with the unyielding and negative position which, unfortunately, Virchow persists in assuming towards the doctrine of evolution.” It probably never occurred to Haeckel that the argument which he here uses to meet Virchow’s opposition to evolution, would serve quite as effectively as a reply to his own opposition to Socialism. As regards Haeckel’s “often quoted declarations against” Socialism, “they have obtained great favor in wide circles, only because of the high authority which this famous naturalist enjoys in an entirely different domain of science. His biogenetic principle, discovered in embryology, “introduced a grand advance in that science thirty years ago. This great and lasting service rendered by him has, however no connection whatever with the unyielding and negative position which, unfortunately,” Haeckel “persists in assuming towards the doctrine of” Socialism. Haeckel’s complaint that Virchow could not judge the merits of evolution because he was not a zoologist, is well taken. But the Socialist has as good or better right to assert that Haeckel was incapable of estimating the relationship of Socialism to Darwinism, for he certainly knew a good deal less about Socialism than Virchow knew of zoology. This is precisely the trouble with Haeckel’s criticism of what he calls Socialism. Of the theories of Karl Marx and the modern scientific Socialists, he knew absolutely nothing. The Socialism he condemned had been abandoned by the Socialists themselves, nearly thirty years before his criticism was made.