384 MR. G. J. ROMANES OlS" PHTSIOLO&ICAL SELECTION. 



underrated, as it now seems probable, the frequency and im- 

 portance of modifications due to spontaneous variability "*, by 

 which be means unuseful modifications. And be proceeds to 

 give a number of examples. 



Elsewhere (p. 158) he points out that modifications which 

 appear to present obvious utility are found on further examina- 

 tion to be really useless. This latter consideration, therefore, 

 may be said to act as a foil to the one against which I am arguing, 

 viz. that modifications which appear to be useless may neverthe- 

 less be useful. But here is a still more suggestive consideration, 

 also derived from Mr. Darwin's writings. Among our domes- 

 ticated productions, changes of structure — or even structures 

 wholly new — not unfrequently arise which are in every way 

 analogous to the apparently useless distinctions between wild 

 species. Take, for example, the following most instructive 

 case : — 



" Another curious anomaly is offered by the appendages de- 

 scribed by M. Eudes-Deslongchamps as often characterizing the 

 Normandy pigs. These appendages are always attached to the 

 same spot, to the corners of the jaws ; they are cylindrical, about 

 three inches in length, covered with bristles, and with a pencil 

 of bristles rising out of a sinus on one side ; they have a carti- 

 laginous centre with two small longitudinal muscles ; they occur 

 either symmetrically on both sides of the face, or on one side 

 alone. Richardson figures them on the gaunt old ' Irish Grrey- 

 hound pig ;' and Nathusius states that they often occasionally 

 appear in all the long-eared races, but are not strictly inherited, 

 for they occur or fail in the animals of the same litter. As no 

 wild pigs are known to have analogous appendages, we have at 

 present no reason to suppose that their appearance is due to re- 

 version ; and if this be so, we are forced to admit that a somewhat 

 complex, though apparently useless, structure may be suddenly 

 developed without the aid of selection " f. 



Now, if any such structure as this occurred in a wild species, 

 and if any one were to ask what is the use of it, those who rely 

 on the argument from ignorance would have a much stronger 

 case than they usually have ; for they might point to the carti- 

 lage supplied with muscles, and supporting a curious arrange- 



* ' Origin of Species,' ed. 6, p. 171. Also, and even more strongly, ' Descent 

 of Man,' p. 367. 



t ' Variation,' &c. vol. i. pp. 78-9. 



