Since Darwin’s death, his theory, which in Germany more than elsewhere received its development, has but few decisive steps in advance to point to, even though the circle of its adherents has been enlarged and though in many respects and in special directions it has been rendered more complete and placed upon a firmer foundation. It is a gratifying fact, that most, if not all, of the recent discoveries in zoology, palæontology, and particularly in developmental history, are easily and completely reconcilable with the principles originally established; so that the views which we have reached on this subject have lost more and more the characters of a purely hypothetical fabric. But the accurate investigations of developmental history have unquestionably furnished the most important material in proof of the theory in question, and the principles established in this department, in the main the results of the labors of German investigators (E. von Baer, Fritz Müller, E. Haeckel), have been verified in a truly surprising manner. It is true that Darwin himself in no way undervalued the importance of the results of the studies in question, but how little the facts known at the time of the enunciation of his theory of natural selection sufficed, is most clearly proved by the fact that E. von Baer and Louis Agassiz, who at that time were perhaps the greatest authorities in embryology, assumed a hostile attitude towards the new Darwinian theory. Agassiz’s combination of the points of agreement of palæontology and embryology, his explanation of extinct forms as “prophetic types,” proved a veritable hindrance to the perception of the truth, and Carl Vogt, who was his co-worker at that time, appears to have been the last to set up any opposition to the “fundamental biogenetic principle,” that the development of the individual repeats in an abbreviated form the history of his race. Vogt, formerly the champion of advanced views, appears to-day as the leader of the small band of the opposition.