account for such examples of extreme evolution as those presented by the special structures of the worker-bee, while the lapsing of inborn variations is sufficient to account for such examples of equally extreme retrogression as those presented by the reproductive organs of that animal, we are entitled to assume that the evolution or the retrogression of the eye is due to the accumulation or to the lapsing of inborn variations alone, unless it can be shown that these causes do not in whole or part sufficiently account for the phenomena, but that these latter must in whole or part be attributed to other causes—i.e. to the effects of use or disuse, to the accumulation or to the lapsing of acquired variations.
No serious attempt is made by Mr. Spencer to prove that Cessation of Selection is insufficient to account for retrogression in the eyes of cavern-dwelling species; he sets himself to prove merely that "economy of nutrition" is insufficient, and appears to think that this is all that is necessary. Having destroyed a non-essential outwork he imagines he has conquered the fortress. His error is indicated by Professor Romanes (Contemporary Review, April 1893), but he still maintains his view (pp. 66–7). He is criticizing Professor Weismann's theories, and insists that with that scientist Panmixia—i.e. Cessation of Selection—"is clearly identified with the selection of smaller variations, and for the reason that economy of nutrition is so achieved." I am not concerned in defending Professor Weismann, and if he believes as Mr. Spencer thinks he believes, in my opinion he is wrong. I am bound to say, however, that his works have conveyed an impression to me entirety different.
When at last Mr. Spencer's attention is forced to Cessation of Selection as a cause of retrogression, he discusses—and dismisses the subject in the following words—
