445 



SCIENTIFIC SIDE-LIGHTS 



Microscope 

 Mimicry 



is in every physical way admirably adapted 

 to be a favorable medium for bacteria. It 

 is constituted of all the chief elements of 

 the food upon which bacteria live. It is 

 frequently at a temperature favorable to 

 their growth. It is par excellence an ab- 

 sorptive fluid. . . . Yet, whilst this gen- 

 eral fact is true, we must emphasize at the 

 outset the possibility and practicability of 

 securing absolutely pure sterile milk. Re- 

 cently some milking was carried out under 

 strict antiseptic precautions, with the above 

 sterile result. The udder was thoroughly 

 cleansed, the hands of the milker washed 

 with corrosive sublimate and then pure wa- 

 ter, the vessels which were to receive the 

 milk had been carefully sterilized, and the 

 whole process was carried out in strict clean- 

 liness. The result was that the sample of 

 milk remained sweet and good and con- 

 tained no germs. It should be stated that 

 the first flow of milk, washing out the milk- 

 ducts of the udder, was rejected. This fact 

 of the sterility of cleanly drawn milk is not 

 a new one, and has been established by many 

 bacteriologists. Milk, then, is normally a 

 sterile secretion. NEWMAN Bacteria, ch. 6, 

 p. 180. (G. P. P., 1899.) 



2178. MIMICRY, PROTECTIVE 



Brilliant, Inedible Moths Mimicked by 

 Others. [A showy] protected group in the 

 Eastern tropics is that of the beautiful day- 

 flying moths forming the family Agaristidce. 

 These are usually adorned with the most 

 brilliant colors or conspicuous markings, 

 they fly slowly in forests among the butter- 

 flies and other diurnal insects, and their 

 great abundance sufficiently indicates their 

 possession of some distastefulness which 

 saves them from attack. Under these con- 

 ditions we may expect to find other moths 

 which are not so protected imitating them, 

 and this is the case. One of the common 

 and wide-ranging species (Ophthalmis lin- 

 cea), found in the islands from Amboyna to 

 New Ireland, is mimicked in a wonderful 

 manner by one of the Liparidce. . . . Both 

 insects are black, with the apex of the fore 

 wings ocher-colored, and the outer half of 

 the hind wings bright orange. WALLACE 

 Darwinism, ch. 9, p. 167. (Hum.) 



2179. Colors of Grouse 



and Ptarmigan. The close imitation in the 

 plumage of these birds [the grouse and 

 ptarmigan of Scotland] of the general tint- 

 ing and mottling of the ground on which 

 they lie and feed is apparent at a glance, 

 and is best known to those who have tried 

 to see grouse or ptarmigan when sitting, and 

 when their position is indicated within a 

 few feet or a few inches by the trembling 

 nostrils and dilated eyeballs of a steady 

 pointer dog. In the case of the common 

 grouse, as the ground is nearly uniform in 

 color throughout the year, the coloring of 

 the bird is constant also. But in the case 

 of the ptarmigan, it changes with the 

 changing seasons. The pearly grays, which 



in summer match so exactly with the lichens 

 of the mountain peaks, give place in winter 

 to the pure white which matches not less 

 perfectly with the wreaths of snow. AR- 

 GYLL Reign of Law, ch. 4, p. 110. (Burt.) 



218O. Dependent on Will 



Moth Purposely Folds in His Brilliant 

 Wings.- There are some forms of mimicry 

 which are wholly independent of any action 

 on the part of the animals-themselves, and 

 this kind of mimicry is especially common 

 in this class of insects. They are often 

 made of the shape and of the color which 

 are most like those of the surrounding ob- 

 jects in their habitat. They have nothing 

 to do except to sit still, or perhaps to 

 crouch. But there are other forms of mimic- 

 ry in which the completeness of the decep- 

 tion depends on some cooperation of the 

 animal's own will. This [the sudden disap- 

 pearance of a brilliant Italian moth, appar- 

 ently transformed into a withered leaf] was 

 one of these. The splendid margins of the 

 upper wings, with the peculiar shape and 

 their shining color, had to be concealed; and 

 so, by an effort which evidently required the 

 exertion of special muscles, these margins 

 were somehow folded down reverted cov- 

 ered up, and thus hidden out of sight. The 

 remainder of the wings, or the under-sur- 

 faces which were now made uppermost, were 

 so colored and so crumpled up that they imi- 

 tated exactly the dried and withered leaves 

 around. ARGYLL Unity of Nature, ch. 3, p. 

 52. (Burt.) 



2181. Grasshopper Re- 

 sembling Wasp. A [special] case of mimic- 

 ry not yet noticed by any naturalist is seen 

 in [a species of] grasshopper common in La 

 Plata (Rhcmalea speciosa, of Thunberg). 

 This is an extremely elegant insect; the 

 head and thorax chocolate, with cream-col- 

 ored markings; the abdomen steel-blue or 

 purple, a color I have not seen in any other 

 insects of this family. The fore wings have 

 a protective coloring; the hind wings are 

 bright red. When at rest, with the red and 

 purple tints concealed, it is only a very 

 pretty grasshopper, but the instant it takes 

 wing it becomes the facsimile of a very 

 common wasp of the genus Pepris. These 

 wasps vary greatly in size, some being as 

 large as the hornet; they are solitary, and 

 feed on the honey of flowers and on fruit, 

 and, besides being furnished with stings like 

 other wasps though their sting is not so 

 venomous as in other genera they also, 

 when angry, emit a most abominable odor, 

 and are thus doubly protected against their 

 enemies. Their excessive tameness, slow 

 flight, and indolent motions serve to show 

 that they are not accustomed to be inter- 

 fered with. All these strong-smelling wasps 

 have steel-blue or purple bodies and bright 

 red wings. So exactly does the Rhomalea 

 grasshopper mimic the Pepris when flying 

 that I have been deceived scores of times. 

 I have even seen it on the leaves, and after 



