"What marvel is there," he asks, "that constant conditions acting upon structures which are similar should produce similar results? It is in this sense that the paradox of Leibnitz is true, and we can be said 'to acquire an innate idea;' only the idea is not acquired independently of experience, but through the process of experience similar to that which originally produced it." {231a} The impression left upon me is that he is all at sea for want of the clue with which Professor Hering would have furnished him, and that had that clue been presented to him a dozen years or so earlier than it was he would have adopted it. As regards Mr. Romanes the case is different. His recent work, Mental Evolution in Animals, {231b} shows that he is well aware of the direction which modern opinion is taking, and in several places he so writes as to warrant me in claiming his authority in support of the views which I have been insisting on for several years past. Thus Mr. Romanes says that the analogies between the memory with which we are familiar in daily life and hereditary memory "are so numerous and precise" as to justify us in considering them to be of essentially the same kind. {232a} Again he says that although the memory of milk shown by new-born infants is "at all events in large part hereditary, it is none the less memory" of a certain kind. {232b} Two lines lower down he writes of "hereditary memory or instinct," thereby implying that instinct is "hereditary memory." "It makes no essential difference," he says, "whether the past sensation was actually experienced by the individual itself, or bequeathed it, so to speak, by its ancestors. {232c} For it makes no essential difference whether the nervous changes . . . were occasioned during the lifetime of the individual or during that of the species, and afterwards impressed by heredity on the individual." Lower down on the same page he writes:-- "As showing how close is the connection between hereditary memory and instinct," &c. And on the following page:-- "And this shows how closely the phenomena of hereditary memory are related to those of individual memory: at this stage . . . it is practically impossible to disentangle the effects of hereditary memory from those of the individual." Again:--