190 



THE AMEEICA^ ENTOMOLOGIST. 



varies more or less in different species belong-ing 

 to the same group — as we see ladies who are all 

 of them dressed in one and the same fashion 

 differ slightly from each other in the cut and in 

 the color of their garments— hut still it is one 

 and the same liverj^ To the above remarkable 

 generalization has been recently given the name 

 of the Law of the Unity op Coloration. We 

 may add here that while the different species of 

 the Danais family have wings that are some- 

 what longer than usual, in proportion to their 

 breadth (see Fig. 132), those of the Pieris 

 family usually have wings of rather less than 

 medium length. 



So far so good. "We see flitting about iu the 

 great Valley of the Amazon vast swarms of long- 

 winged butterflies, gorgeously dressed iu red, 

 orange, yellow, white and black ; and certain 

 short-winged butterflies, in very much smaller 

 numbers, whose proper livery is but the plain 

 black and white that befits a funeral. We see 

 the former enjoy an entire immunity from the 

 attacks of all predaceous animals, and the latter 

 snapped up by every hungry Dragon-fly or 

 Asiliis-fiY that happens to come across them. 

 Will it be believed, now, that there are certain 

 particular species of the homely, much perse- 

 cuted, short-winged group, that assume the 

 livery worn by certain particular species of 

 their gaily-dressed compatriots, and actually 

 even copy their elongated wings? Yet such is 

 the indubitable fact. In the Memoir by Mr. 

 Bates, which has been already referred to in a 

 foot-note, will be found beautiful colored fig- 

 ures, in the highest style of art, both of the 

 species that mimick and of those that are mim- 

 icked; and no one that looks at those figures 

 with an unprejudiced eye can believe for a 

 moment that the resemblance is merely acci- 

 dental. We might as well suppose that it was 

 only by accident, and not with any deliberate 

 design of following a prevailing fashion, that 

 the ladies, throughout the whole civilized world, 

 have within the last few years taken to wearing 

 hoop-skirts and long trailing dresses. What is 

 still more remaikable, although most of these 

 species are quite local, the mimickers are always 

 found in the same district with the mimicked, 

 and usually fly iu company with them. The 

 number of such cases met with in the Valley of 

 the Amazon amounts to many scores, besides 

 several analogous instances quoted by Mr. Bates 

 as occurring not only in South America, but also 

 in the Old World. Even the practised glance 

 of the experienced bug-hunter is deceived by 

 the close resemblance, when the imitators and 

 the imitated are on the wing, and fails to distin- 



guish the one from the other ; although, as soon 

 as they are captured, the eye perceives at once 

 that there are structural differences between the 

 two, which separate them as widely from each 

 other as a camel is separated from a buffalo. 

 On this subject, we cannot do better than to 

 quote Mr. Bates's own language : 



These Imitative resemblances, of which hundreds of 

 instances could be cited, are full ot interest, and ml us 

 ■with the greater astonishment the closer we investigate 

 them; for some show a minute and palpably intentional 

 likeness which is perfectly staggering. I have found 

 that those features of the portrait are most attended to 

 by nature, >vhich produce the most effective deception 

 when the insects are seen in nature. The faithfulness 

 of the resemblance, in many cases, is not so striking 

 when thev are seen iu the cabinet, Although I had 

 daily practice in insect-collecting for many years, and 

 was always ou my guard, 1 was constantly deceived by 

 them when in the woods, (p. 507.) 



Mr. Bates accounts for these singular cases of 

 mimickry by supposing that, ages and ages ago, 

 certain individuals of this plainly-dressed and 

 mnch-persecutedPieris Family happened to vary 

 slightly, so as to resemble slightly some species 

 or other belonging to the gaily-dressed and un- 

 palatable Dcmai* Family; that, in consequence 

 of this slight resemblance, they were sometimes 

 mistaken for their more fortunate compatriots 

 by cannibal animals, which would otherwise 

 have preyed upon them forthwith ; and conse- 

 quently that tliey survived long enough to pro- 

 pagate their species, while almost all the iudi- 

 viduals that had riot varied in this particular 

 manner perished prematurely by a violent death. 

 Now, we know that, in the language of breeders 

 and stock-raisers, " like produces like," which 

 is what naturalists express by the well-known 

 term of the " Law of Inheritance." Hence the 

 descendents of this primordial race of imitative 

 butterflies would naturally, most of them, vary 

 in the same manner as did their ancestors from 

 the normal type ; and some of them would proba- 

 bly vary in a still more marked manner and in 

 the same direction. These last individuals, as 

 they would bear a still closer resemblance to the 

 unpalatable butterflies, would of course stand a 

 still better chance of surviving and propagating 

 their species, in the course of that great Struggle 

 for Existence, which we see going on all around 

 us, not only among the inferior animals, but 

 among the Human Species itself. By the per- 

 petual repetition of this process, duriug indefi- 

 nite ages, that perfect imitation of the imitated 

 butterfly would at length be formed, which at 

 first view appears so utterly inexplicable. And 

 when it had once been formed, the very same 

 process that originally formed it would after- 

 wards keep it up to the standard of perfection. 

 For all individuals, that varied in a backward 

 direction towards the primordial type, would 



