From pedagogy to evolution is but a step, at least it is in Ziller’s development of Herbart’s ideas. It is true, Ziller has taken a decided stand against Darwinism, for Ziller works with two contradictory ideas; but his theory of education possesses points of resemblance and analogy to the Darwin-Haeckel theory of development. According to Ziller, each individual passes, also intellectually, through all the stages of development that mankind at large has passed through, only in a shorter time; and it is in conformity with such succession that the order of the various courses of a pedagogical system is to be arranged. Following Ziller’s precedent, PROFESSOR VAIHINGER, of Halle, in his treatise _Naturforschung und Schule_ (Science and the Schools), has taken up the school-reform initiated by Professor Preyer, and has expressly transferred the fundamental law of biogenesis to pedagogy. How instruction is to be arranged under this point of view, cannot be explained in this letter, which is already long enough. We shall simply remark that the idea has found in Germany a large number of both friends and opponents. The opponents have recently been joined by a natural scientist, DR. HAMANN, professor of zoology in Göttingen, who has just published a book under the title _Entwicklungslehre und Darwinismus_ (Evolution and Darwinism),[54] in which he does not combat the theory of evolution itself, but simply the Darwin-Haeckelian form of that theory, placing himself in the ranks of His and Hensen. The book appeared almost simultaneously with the fourth edition of HAECKEL’S _Anthropogeny_,[55] but the author, nevertheless, in his supplementary remarks, discusses the “apology” which Haeckel subjoined to his work. Haeckel’s book needs no recommendation in scientific circles; it will be sufficient to state that the work has been subjected to essential alterations, but that its fundamental features have remained the same. A new psychology, on the Darwinian basis, by Prof. FRITZ SCHULTZE of Dresden, is now in course of publication, entitled _Vergleichende Seelenkunde_ (Comparative Psychology[56]). The first part, which treats of the fundamental principles of physiological psychology, has already appeared. On the completion of the work we shall have occasion to return to it. CHR. UFER. FOOTNOTES: [48] _Problematic Child-natures._ Leipsic, 1890, Robert Vogtländer. [49] _Faults of Character in Children, A System of Instruction for School and Home._ Leipsic. Eduard Heinrich Mayer. [50] Compare also, _The Educational Review_ (New York), Vol. II, page 30. [51] _Psychologie als Wissenschaft_, § 5. [52] Salomon Hirzel, Leipsic. [53] Hamburg, 1891, Leopold Voss. [54] Jena, 1892, Hermann Costenoble. [55] Leipsic, 1892, Engelmann. [56] Leipsic, 1892. CRITICISMS AND DISCUSSIONS. A LETTER FROM MR. HERBERT SPENCER. _To the Editor of The Monist_: