My dear Poulton,--Many thanks for your interesting letter. From it I quite understand your views about the relation between reproduction and repair; are they those of Weismann or altogether your own? And have they, as yet, been published anywhere? If not, I suppose it is undesirable to allude to them in public? The theory is ingenious, but seems to sail rather near Pangenesis (as do many of the latter amendments of germ-plasm by W.); and I should have thought that the limbs of salamanders, &c., are too late products, both phylogenetically and ontogenetically, to fall within its terms. I also see better what you mean about Sphex. But Darwin's letter in 'Mental Evolution in Animals' seems to me to meet (or rather to anticipate) the 'difficulty.' Of course, he did not suppose that the insects' knowledge of 'success' goes further than finding out and observing the best place to sting in order to produce the maximum effect. The analogy of Cymphs is apposite; but is it the fact that there is any species whose localisation is really comparable with that of Sphex? Contrasting Weismann's account with Fabre's, I should say not. As for neuter insects (which you mentioned at Newcastle), Darwin allows that they constitute one of the most difficult cases to bring under natural selection, seeing that this has here to act at the end of a long lever of the wrong kind, so to speak. Read Perrier's preface to French translation of 'Mental Evolution in Animals,' and observe how good his suggestion is, on the supposition that Lamarckian principles have any applicability at all. Lastly, at Newcastle you said something that seemed to imply a doubt upon such facts as Lord Morton's mare. Do you really doubt such facts? I cannot suppose it. There are plenty of white stoats hereabouts, I believe, though I have never actually seen them, because I do not stay late enough in the year. I have told my keeper to try to catch some without injuring them, and, if he succeeds, to send them straight to the Zoo. The experiment would be a very interesting one. But the keeper says that even here the whiteness depends as to its intensity upon the amount of snow in different seasons. He is most positive about this; he says it depends upon snow, and not on cold. However, I do not quote him as an authority in science, although he certainly is an intelligent and observing man. Regarding the Royal Institution, an after Easter course by you would be doubly interesting, because before Easter I have to give one on the 'Post-Darwinian Period,' which will be mainly concerned with Weismann. Your lectures might then serve as a counter-irritant, therefore I will do anything I can to bring them about, only, not being on the managing body, I can help merely by backing any application you may make. And, of course, there ought to be no difficulty about it. Only let me know if you should want backing.