88 in several places taken pains to state his views upon this highest of subjects. To one of these passages (from the work De Gene- ratione Exercit. Quinquagesima, p. 385, ed. 1766; p. 370, ed. Dr. Willis), as Mr. E. B. Tylor has pointed out to me, Professor His of Leipzig, a worker whom Harvey would have hailed as a colleague, has referred in one of his always excellent papers, published in the Archiv fur Anthropologic, Bd. iv. 1870, p. 220, on 'Die Theorien der geschlechtlichen Zeugung.' It is just in the investigation of the problems indicated in these last words that, as has often been remarked, the question of the existence of other than purely material forces presses itself most closely upon the mind ; and hence, perhaps, the repetition by Harvey of his views regarding it, more than once or even twice, in his treatise just referred to (see Exercit. 49, p. 730 ; Ex. 50, p. 385 ; Ex. 54, pp. 419, 420). These statements are all to the same purpose. I have chosen one of them — the last one of the three just cited (not the one quoted by Professor His) — to repeat here, because, besides its philoso-
