SINCE the publication of Prof. T. M. Lowry's article in NATURE of February 20, 1926, p. 271—an article which, I observed, drew a gentle remonstrance from Prof. Armstrong in the issue of April 17—I have felt that some rejoinder was desirable, but was held back by the fact that adequately to criticise Prof. Lowry's views would require considerably more space than the article itself, since almost every statement made, far from possessing the definiteness which Prof. Lowry attributes to it, is highly controversial, and it usually requires less space to make an assertion than convincingly to refute it. But perhaps I may be allowed to point out that so far back as 1916 (J.C.S., 109, 1211–1216, 1222–1224) I offered a reasoned criticism of most of the views which Prof. Lowry has so industriously advocated in the last few years, and that hitherto Prof. Lowry has not attempted any reply to these criticisms. Incidentally it may be suggested that Prof. Lowry does his thesis some disservice by a policy of aloofness from valid criticism directed against it. It may, of course, be that the criticisms are unanswerable, in which case Prof. Lowry's views require modification.