Herewith I return, with many thanks, a pamphlet by Kerner, numbered 738. In my experiments with electric spark illumination on plants, I notice that the seedlings, although so wonderfully heliotropic, never form chlorophyll, even if exposed to a continuous stream of sparks for 30 hours on end, while they will bend through 90° in seven hours to single sparks following one another at one per second. This proves that there is no connection at all between heliotropism and formation of chlorophyll, or _vice versa_--a point which I cannot find to have been hitherto stated. Do you happen to know if it has been? If you do not happen to remember anything bearing on this subject, do not trouble to search or to answer. Wallace's book[65] strikes me as very able in many parts, though singularly feeble in others--especially the last chapter. He has done but scant justice to Gulick's paper. Had he read it with any care, he might have seen that it fully anticipates his criticism on mine. But I think he deserves great credit for nowhere chuckling. From the first he has been consistent in holding natural selection the sole factor of organic evolution--leaving no room for sexual selection, inheritance of acquired characters, &c., &c. And now that he had lived to see an important body of evolutionists adopting this view, there must have been a strong temptation to 'I always told you so.' Yet there is nowhere any note of this, or even so much as an allusion to his previous utterances on the subject. _To E. B. Poulton, Esq._ Geanies, Ross-shire: November 2, 1889. My dear Poulton,--Continuing our antipodal correspondence, and taking the points in your last letter _seriatim_, I quite saw that your theory of repair was 'the logical outcome of Weismann's' (being, in fact, a direct application of his views on phylogeny to the case of repair); but I did not know whether the outcome had been traced by him or by yourself. Now, I understand, I may allude to it as yours. Again, what I meant about regeneration of entire limbs, &c., was that, to meet such cases, your diagram would require modification in the way that you now suggest. Has it occurred to you as an argument in favour of this suggestion (_i.e._ that the 'potentiality' of somatic germ-plasm may in such cases be arrested in its process of ontogenetic diffusion), that Darwin has shown, or at least alleged, that all such cases may be traced to special adaptation to special needs, dangers, &c.--so that the arrest may have been brought about in these cases by natural selection?