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Show 212 DARWINISM CHAP. its station· a,nd it ha.s boon seen to capture flies which came ) to tho flowers. But the most curious and beautiful case of alluring protection is that of a wingless Mantis i~ India, '~hich is so formed and coloured as to resemble a pmk orchis or some other hntc'lstic flower. The whole insect is of a bright pink colonr, the larae and oval abdomen looking like the labellum of an orchid. On each side, the two posterior legs have im mensely dilated and flattened thighs which rep.re~ent the petals of a flower, while the neck an~ forelegs _1m1tatc the upper sepal and column _of an _orchid. The 1~sect rests motionless, in this symmetrical attltude, among bngbt green foliaae beina of course very com;picuous, but so exactly resembb'l ina ab flower that butterfb0 es an< 1 oth er m. sccts sctt 1c upon it ~nd arc instantly captured. It is a living tmp, baited in the most alluring manner to catch the umvary flower-haunting insects.1 The Coloration of Birds' Eggs. The colours of birds' eggs have long been a difficulty on the theory of adaptive coloration, bccanse, in so ma11y cases it has not been easy to see what can he the use of the particular colours, which are often so bright and conspicuous that they seem intended to attract attention rather than to be concealed. A more careful consideration of the subject in all its bearings shows, however, that here too, in a, great number of cases, we have cxa.mplcs of pro,tectivc coloration. "\Yh cn, therefore, we cannot sec the meaning of the colour, we m:ty suppose that it has been protective in some ancestral form, and, not being hurtful, has persisted under changeu conditions which rendered the protection needless. We may divide all eggs, for our present purpose, into two 1 A ben.utiful drawing of this rare insect, Hymenopus bicornis (in tl1c nymph or active pupa state), wn.s kindly sent n1e by Mr. Wood-Ma ·on, Curat or of the Indian Museum at Cn.lcutta. A species, very si111ilar to it, inhahiLH .J av:1, where it is said to resemble a pink orchid. Other M:wtiu a~ , of the gt>nns Gon •ylus, luwe the anterior part of the thorax dilated aml colomed eiti.lt'r wl1ite, pink, or pmple; and they so closely re. emble flowers that, ac<'Or1l 11~g to Mr. Woo<l-Mason, one of them, having a bright violet-blue prothorat•Je sl1iel•l, was found in Pegu by a botanist, and was for a moment mistaken by him for a flower. See Proc. Ent. Soc. Lond., 1878, p. liii. VIII ORIGIN AND USES OF COLOUR IN ANIMALS 213 great divi~ions ; those :which arc white or nearly so, a~d those which arc distinctly coloured or spotted. Egg-shells bcmg composed mainly of carbonate of lime, we may assume thn.t the primitive colour of biru ' eggs was "~ hitc, a colour th<~t prevails now a.mong the other cgg-bcarmg vcrtcbratcs-bza,rds, crocodile , turtle. , and snakes ; and we might, therefore, expect that this colour would continue where its presence had no dis<tdvantages. Now, as a matter of f<tct, we find that in all the groups of birds which la,y their eggs in concc:tlcd pbccs, whether in holes of trees or in the ground, or in domed or covered nests, the eggs arc either pure white or of very paJc uniform coloration. Snch i.· the asc with ki1wfishcr., beecaters, penguin , and puffins, which nest in holes in the around· with the rrrcat pa.rrot family, the woodpeckers, the b ' u 0 0 rollers, hoopoc., tro<,.ons, owl·, and :ome others, which bmld m holes in trees or other concealed plrtccs; while ntartins, wrens, willow-warblers, and Australian finches, build domed or covered nests, and usually ha,ve white egg . There arc, however, many other birds \•rhich lay their white ecro·s in open nests; a11d these aff'orcl some very interestin:~ xamples of the vari d modes by which concc<tlrncut may be 0 obtained. All the duck tribe, the gr bcs, and the pheasants belong to this class; bnt these birds all have t~e habit of covering their ego·s with dead leaves or other n1atcrml whenever they leave the nest, ·o as cfl'cctnally to conceal them. Other birds, as the short-cared owl, the goatsuckcr, the partridge, ami. some of the AustrnJia,n ~ronnel pigeons, lay their white or pale egg~ on the bare sml ; bnt m these cases the birds themselves a.rc protectively colonrccl, so that, when sitting, they arc almost invisihlc; and they ha.vc the habit of sitting close and almost continuou ly, thus effectually concealing their eggs. Picrcons and doves offer a very curious case of the protection ;f exposed eggs. They usmtlly hnild very slight and loose nests of . ticks and twigs, so open that light can he seen through them from below, while they arc g nerally well concealed by foliage above. Their eggs arc white and shining; yet it is a difficult matter to discover, from beneath, whether there arc c<ro·s in the nest or not, while they n.rc well 00 . hidden by the thicl<; foliage above, The Australian podarg1- |
