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Show 218 INSTINCT. CHAP. VII. dd that according to Dr. Gray generated. I may a 'the European cuckoo has and to some other observer~, 1 e and care for her own not utterly lost all materna ov offspring. . f birds laying their eggs in The occasional ha~It 0 f tl e same or of a distinct other birds' nests, either 0 1 with the Gallinacere ; . . t very uncommon . 1 speCies,. IS no lains the origin of a singu ar and this perhaps . e~p rou of ostriches. For several instinct in the alhe tg . pthe case of the American . h at leas In d hen ostrw . es, first a few eggs in one nest an species, unite and la~ th e are hatched by the males. then in another ; an b b~s be accounted for by the fact This instinct m~y P:~a~ [number of eggs; but, as in of the hens layingk gt 'ntervals of two or three days. h f the cue oo, a I · t e case o . f the American ostnch has not This instinct, ho;e;er,. ofor a surprising number of eggs as yet been per e~ e l . so that in one day's hunting lie strewed overl t ethpaanmt~enty lost and wasted eggs. I · k d up no ess . · pw e 't' nd always lay therr eggs m M b are parasi w, a any ees other kinds. This case is more re-the nests of ~~~:: of the cuckoo ; for these bee~ ha:e markable th~ . . t b t their structure modified m not only their Instmc s u . . . . h do not d 'th their parasitic habits' for t ey accor antche Wpl ollen-col le c tI' ng apparatus which would be possess e t £ d for their own young. necessary i! the:y ha~ to s t~e h~~idre (wasp-like insects) Some species, like"' Ise, o . p. d M Fabre has lately are parasitic on other species.' ~n that although the sho·wn good reason for believmg. burrow and Tachytes nigra generally makes ·~ts o"rnlarvre to feed stores it with paralyse~ ~rey fo~~;s o:~urrow already on, yet that when this Insect "t takes advantage made and stored by another sphex, I . 't'c In f th ccasion parasi I . of the prize, and becomes or e o koo I can this case, as with the supposed case of the cue ' CHAP. VII. SLA YE-MAKING INSTINCT. 219 see no difficulty in natural selection making an occasional habit permanent, if of advantage to the species, and if the insect whose nest and stored food are thus feloniously appropriated, be not thus exterminated. Slave-malcing inBtinct.-This remarkable instinct was first discovered in the Formica (Polyerges) rufescens by Pierre Huber, a better observer even than his celebrated father. This ant is absolutely dependent on its slaves ; without their aid, the species would certainly become extinct in a single year. The males and fertile females do no work. The workers or sterile females, though most energetic and courageous in capturing slaves, do no other work. They are incapable of making their own nests, or of feeding their own larvre. When the old nest is found inconvenient, and they have to migrate, it is the slaves which determine the migration, and actually carry their masters in their jaws. So utterly helpless are the masters, that when Huber shut up thirty of them without a slave, but with plenty of the food which they like best, and with their larvre and pupre to stimulate them to work, they did nothing; they could not even feed themselves, and many perished of hunger. Huber then introduced a single slave (F. fusca), and she instantly set to work, fed and saved the survivors ; made some cells and tended the larvre, and put all to rights. What can be more extraordinary than these well-ascertained facts ? If we had not kno"rn of any other slave-making ant, it would have been hopeless to have speculated how so wonderful an instinct could have been perfected. Formica sanguinea was likewise first discovered by P. Huber to be a slave-making ant. This species is found in the southern parts of England, and its habits have been attended to by Mr. F. Smith, of the British L2 |