I quite agree that Weismann's suggestion about causes of variability is an admirable one. But it has always seemed to me that it is comprised under Darwin's general category of causes internal to the organism (or, in his terminology, causes due to 'the nature of the organism'). But besides this, he recognised the category of causes external to the organism (or the so-called Lamarckian principles of direct action of environment, _plus_ inherited efforts of use and disuse). Now, anyone who accepts this latter category as comprising _veræ causæ_, obviously has a larger area of causality on which to draw for his theoretical explanations of variability, than has a man who expressly limits the possibility of such causes to the former category. This is all that I had in my mind when writing the line in the 'Contemporary Review' which led you to suppose that I was expounding W. without having read him; and although I freely allow that the meaning was one that required explanation to bring out, you may remember that this meaning had nothing whatever to do with the subject which I was expounding, and therefore it was that I neglected to draw it out. You will observe that, so far as the present matter is concerned, it does not signify what views we severally take touching the validity of Lamarckian hypotheses. The point is, that anyone who sees his way to entertaining them thereby furnishes himself with a larger field of causality for explaining variations than does a man who limits that field to causes internal to organisms--even though, like W., he suggests an extension of the latter. And now about the 'Athenæum.' I fear you think I have been taking an unfair opportunity of giving you a back-hander. In point of fact, however, I never do such things; and the more reason I have for anything like hitting back (which, however, is entirely absent on the present occasion), the more careful should I be to avoid any appearance of doing so in an unsigned review. I neither wrote, nor have I read the particular review in question. Regarding articulation, read in my 'Mental Evolution in Man,' Mr. Hales' admirable remarks on children having probably been the constructors of all languages. I believe this theory will prove to be the true solution of the origin of _languages_, as distinguished from the faculty of _language_. What you say about the latter being blastogenetic, requires you to unsay what is said by W. Please let me know whether there is anything that you see in my 'cessation of selection' different from W.'s 'Panmixia.' The debate to-day failed to furnish any opposition. Yours very sincerely, G. J. ROMANES. Geanies, Ross-shire, N.B.: October 21. 1889.