A MOCK ARGUMENT. ' 99 



insects.* This imitative apparatus, beginning in a tendency to develop 

 buttons or rattles on the tail (originating, as many herpetologists think, in 

 an incomplete shedding of the skin at that part), and in the inherent dis- 

 position to wag the tail (which is a channel for the expression of surplus 

 energy in all animals), was accounted for through a process of develop- 

 ment by natural selection. This seems to me, as I read, it, remarkably 

 unlikely. It asserts prodigious preparation for very small results, since 

 the insects simulated are never particularly plentiful where the majority 

 of rattlesnakes occur, taking the whole country across; are noisy only a 

 quarter of the year; and the birds to be deceived form only a small por- 

 tion of the reptile's fare. 



There grows in some parts of the Southern States a kind of grass 

 which bears seed-panicles that are so jointed as not only to resemble some- 

 what the caudal appendage of the crotalus, but to rustle with a similar 

 sound when shaken by the wind-. Its popular name is "rattlesnake 

 grass." Why not argue that, through natural selection, the serpent has 

 acquired a tail which, when held erect (as this serpent's tail so often is), 

 shall so resemble the grass-heads among which the reptile frequently lies 

 in ambush that its prey may see no difference, and so may come unwarned 

 within reach of the fangs? Or, if it is assuming too much to take for 

 granted that the grass form is older than the snake form, so that the latter 

 must have changed to suit the former, then why cannot we argue plausi- 

 bly that the plant gradually developed towards its present form because 

 those ancestral plants which more and more nearly approached this appear- 

 ance were more and more avoided by the crushing feet and nibbling teeth 

 of animals which feared the rattlesnake, and hence avoided anything that 

 looked or sounded suspiciously like it ? 



Of course I am not advancing a serious argument in bringing this for- 

 ward, but it seems to me that it is quite as good and logical as the cicada- 

 story or some other theories which I have heard of. That natural selec- 

 tion lias had something or everything to do with the rattle of the crotalus, 

 I cannot but believe; but I fear we do not yet perceive in what manner. 



Although, as I say, I cannot admit that the insect mimicry is worth 

 much consideration, I can see how the noise made by the tail might act 

 as a deadly lure to birds and 6mall mammals by working upon their curi- 

 osity — a weakness particularly noticeable in squirrels. The interesting 



* The summary of this discussion may be found in The American Naturalist, vi., 32, 

 260, and vii., 85. The rattles also form the theme of articles in Harper's Magazine, x., 

 470; in Chambers's Journal, xlix., 641 (copied into the Eclectic and Every Saturday) ; in 

 Tlie Lakeside, v., 252 ; and in the Soutliem Literary Miscellany, xvi., 27. 



