The important problem now presents itself: What is the material, the matter, which is handed down from generation to generation as the basis of inheritance? Weismann, as we know, regarded it as a very complicated structure, part of which by its disintegration became the foundation of individual embryology. We have disproved, on the authority of many facts, the latter part of this assumption; but of course the first part of it may turn out to be true in spite of this. We have no means at present to enable us to say *a priori* anything positive or negative about the important question of the nature of that matter, the continuity of which in inheritance is in some sense a self-evident fact, and we therefore shall postpone the answer until a later point of our analytical discussion. ON CERTAIN THEORIES WHICH SEEK TO COMPARE INHERITANCE TO MEMORY It will be advisable first to study some other theoretical views which have been put forward with regard to inheritance. The physiologist Hering, as early as 1876, compared all heredity to the well-known fact of memory, assuming, so to say, a sort of remembrance of all that has happened to the species in the continuity of its generations; and several German authors, especially Semon, have lately made this hypothesis the basis of more detailed speculation. It is not clear, either from Hering’s paper[121] or from Semon’s book,[122] what is really to be understood here by the word “memory,” and, of course, there might be understood by it very different things, according to the author’s psychological point of view. If he is a “parallelist” with regard to so-called psychical phenomena, he would use the word memory only as a sort of collective term to signify a resultant effect of many single mechanical events, as far as the material world of his parallel system comes into account, with which of course the problem of inheritance alone deals; but if he maintains the theory of so-called psycho-physical interaction, the psychical would be to him a primary factor in nature, and so also would memory. As we have said, it is by no means clear in what sense the word “memory” is used by our authors, and therefore the *most* important point about the matter in question must remain *in dubio*. [121] *Ueber das Gedächtnis als eine allgemeine Function der organischen Materie*, Wien, 1870. New edition in *Klassiker d. exakt. Wiss.*, Leipzig, Engelmann. [122] *Die Mneme*, Leipzig, 1904.