I may say, in passing, that the barrenness of incoherent ideas, and the sterility of widely distant species and genera of animals and plants, are one in principle—­the sterility of hybrids being just as much due to inability to fuse widely unlike and unfamiliar ideas into a coherent whole, as barrenness of ideas is, and, indeed, resolving itself ultimately into neither more nor less than barrenness of ideas—­that is to say, into inability to think at all, or at any rate to think as their neighbours do.

If Mr. Spencer had made it clear that the generations of any race are bona fide united by a common personality, and that in virtue of being so united each generation remembers (within, of course, the limits to which all memory is subject) what happened to it while still in the persons of its progenitors—­then his order to Professor Hering and myself should be immediately obeyed; but this was just what was at once most wanted, and least done by Mr. Spencer.  Even in the passages given above—­passages collected by Mr. Spencer himself—­this point is altogether ignored; make it clear as Professor Hering made it—­put continued personality and memory in the foreground as Professor Hering did, instead of leaving them to be discovered “by implications,” and then such expressions as “accumulated experiences” and “experience of the race” become luminous; till this had been done they were Vox et praeterea nihil.

To sum up briefly.  The passages quoted by Mr. Spencer from his “Principles of Psychology” can hardly be called clear, even now that Professor Hering and others have thrown light upon them.  If, indeed, they had been clear Mr. Spencer would probably have seen what they necesitated, and found the way of meeting the difficulties of the case which occurred to Professor Hering and myself.  Till we wrote, very few writers had even suggested this.  The idea that offspring was only “an elongation or branch proceeding from its parents” had scintillated in the ingenious brain of Dr. Erasmus Darwin, and in that of the designer of Jesse tree windows, but it had kindled no fire; it now turns out that Canon Kingsley had once called instinct inherited memory, {40a} but the idea, if born alive at all, died on the page on which it saw light:  Professor Ray Lankester, again called attention to Professor Hering’s address (Nature, July 13, 1876), but no discussion followed, and the matter dropped without having produced visible effect.  As for offspring remembering in any legitimate sense of the words what it had done, and what had happened to it, before it was born, no such notion was understood to have been gravely mooted till very recently.  I doubt whether Mr. Spencer and Mr. Romanes would accept this even now, when it is put thus undisguisedly; but this is what Professor Hering and I mean, and it is the only thing that should be meant, by those who speak of instinct as inherited memory.  Mr Spencer cannot maintain that these two startling novelties went without saying “by implication” from the use of such expressions as “accumulated experiences” or “experience of the race.”