INSTINCT IN INSECTS. i 57 



of man. Yet the European beaver and the oriole give us examples of 

 instincts that go back to a date relatively not very ancient. We 

 know now, too, that the nests of the same species of birds sometimes 

 present remarkable enough variations in different countries. That 

 Darwin should point out with great care these instincts, varying with 

 latitudes, is very natural ; but we should less naturally expect to find 

 a similar fact, in the book of a partisan, of the unchangeableness of 

 instincts. The leaf-cutter, another hymenopterous insect, lays its eggs 

 in little chambers made of bits of leaves which it has rapidly cut. In 

 our country it is always a rose-leaf. Yet, "we are assured," says M. 

 Blanchard, "that our cutter of rose-leaves, finding itself in some place 

 in Russia where there are no rose-bushes, makes its nest with willow 

 or osier leaves." Therefore, instinct must vary in space as it has va- 

 ried in time ! It is not at all the case that the same legionaries are 

 everywhere as dependent on their comrades as those that Peter Huber 

 saw in the environs of Geneva. In England, as in Switzerland, the 

 auxiliaries reared by the dark-red ants take complete care of the larvae, 

 while the legionaries alone go on expeditions ; but in Switzerland the 

 two castes together busy themselves about all works of construction 

 or supply, while in England the legionaries alone go out to gather 

 provisions and materials ; the auxiliaries remain shut up within ; they 

 thus render less service to the community than they do in Switzerland. 

 It will be said, perhaps, that these differences are a very trifling 

 matter. They are, at least, enough to show how the ancient doctrine 

 of Cuvier has been shaken, and how, in the infinite lapse of time, 

 those instincts may have become developed, which mere geographical 

 accidents suffice to modify slightly. The grand solution of instinct is 

 Time ; that immeasurable duration of those geological epochs which 

 our mind holds in contemplation, but of which it can no more form an 

 idea than of the measure of the heavenly spaces. Modern science be- 

 gins to be amazed at those figures of ages which it must count since 

 the rude attempts at primitive human industry. What shall we think 

 of those times, measured by the planet's growth, through which the 

 instinct of the legionary ants may have been originated, defined, and 

 perfected ? The ant not only saw the epoch of the reindeer and the 

 mammoth, and the glaciers of the Jura creeping down the valley of 

 the Rhone it was a contemporary of that period which geologists 

 mark by the lifting of the Alps. The ant is older on the earth than 

 Mont Blanc. They existed already in the Jurassic period, very little 

 different from what they are in our own times. While an inland sea 

 still flowed over the site where later Paris was to stand, they were 

 multitudinous in the central regions of Europe that were out of water. 

 We may judge of this by the mass of their remains ; they fill thick 

 layers of territory at Oeningen, on the shores of Lake Constance, and 

 at Radoboj, in Croatia ; the rock is black with ants, all wonderfully, 

 preserved, with their claws and delicate antennae. Entomologists now 



