It may be expected that I should say something here about Mr. Romanes’ latest contribution to biology—­I mean his theory of physiological selection, of which the two first instalments have appeared in Nature just as these pages are leaving my hands, and many months since the foregoing, and most of the following chapters were written.  I admit to feeling a certain sense of thankfulness that they did not appear earlier; as it is, my book is too far advanced to be capable of further embryonic change, and this must be my excuse for saying less about Mr. Romanes’ theory than I might perhaps otherwise do.  I cordially, however, agree with the Times, which says that “Mr. George Romanes appears to be the biological investigator on whom the mantle of Mr. Darwin has most conspicuously descended” (August 16, 1886).  Mr. Romanes is just the person whom the late Mr. Darwin would select to carry on his work, and Mr. Darwin was just the kind of person towards whom Mr. Romanes would find himself instinctively attracted.

The Times continues—­“The position which Mr. Romanes takes up is the result of his perception shared by many evolutionists, that the theory of natural selection is not really a theory of the origin of species. . . .”  What, then, becomes of Mr. Darwin’s most famous work, which was written expressly to establish natural selection as the main means of organic modification?  “The new factor which Mr. Romanes suggests,” continues the Times, “is that at a certain stage of development of varieties in a state of nature a change takes place in their reproductive systems, rendering those which differ in some particulars mutually infertile, and thus the formation of new permanent species takes place without the swamping effect of free intercrossing. . . .  How his theory can be properly termed one of selection he fails to make clear.  If correct, it is a law or principle of operation rather than a process of selection.  It has been objected to Mr. Romanes’ theory that it is the re-statement of a fact.  This objection is less important than the lack of facts in support of the theory.”  The Times, however, implies it as its opinion that the required facts will be forthcoming by and by, and that when they have been found Mr. Romanes’ suggestion will constitute “the most important addition to the theory of evolution since the publication of the ‘Origin of Species.’” Considering that the Times has just implied the main thesis of the “Origin of Species” to be one which does not stand examination, this is rather a doubtful compliment.

Neither Mr. Romanes nor the writer in the Times appears to perceive that the results which may or may not be supposed to ensue on choice depend upon what it is that is supposed to be chosen from; they do not appear to see that though the expression natural selection must be always more or less objectionable, as too highly charged with metaphor for purposes of science, there is nevertheless a natural selection which is