•216 SPECLiL INSTINCTS. Chap. VII. 



go on slave-making expeditions. In Switzerland the slaves 

 and masters Avork together, making and bringing materials for 

 the nest; both, l)iit cliiefly the slaves, tend, and milk, as it may 

 be called, their aphides ; and thus both collect food for the 

 community. In England the masters alone usually leave the 

 nest to collect Ijuilding-materials and food for themselves, their 

 slaves and larva^. So that the masters in this country receive 

 much less service from their slaves than they do in Switzerland. 



By what steps the instinct of F. sanguinea originated I 

 will not pretend to conjecture. But as ants, which are not 

 slave-makers, Avill, as I have seen, carry off pupoe of other spe- 

 cies, if scattered near their nests, it is possible that such pupaj 

 originally stored as food might become developed ; and the 

 foreign ants thus unintentionally reared would then follow their 

 proper instincts, and do what work they could. If their pres- 

 ence proved useful to the species which had seized them — if it 

 Avere more advantageous to tliis species to capture workers 

 than to procreate them — the habit of collecting pupa? originally 

 for food might by natural selection be strengthened and ren- 

 dered i^ermanent for the very different purpose of raising slaves. 

 When the instinct was once acquired, if carried out to a much 

 less extent even than in our British F. sanguinea, which, as 

 we have seen, is less aided by its slaves tlian the same species 

 in Switzerland, natural selection might increase and modify the 

 instinf"*^ — always supposing each modification to be of use to 

 th(; species — until an ant Avas fcn-med as abjectly dependent on 

 its slaves as is the Formica rufcscens. 



Cell-making Instinct of the IIivc-J3ee. — I will not here 

 enter on minute details on this subject, but Avill merely give an 

 outline of the conclusions at Avhich I have arrived. He must 

 be a dull man Avho can examine the exquisite structure of a 

 comb, so beautifully adapted to its end, without enthusiastic 

 admiration. We hear from mathematicians that bees have 

 jiractically solved a recondite ]irobk'm, and have made their 

 cells of the proper shape to hold the greatest possible amount 

 of hone}', with the least possible consumption of precious Avax 

 in their construction. It has been remarked that a skilful Avork- 

 man Avith fitting tools and measures, Avould find it very difficult 

 to make cells of Avax of the true form, though this is jierfectly 

 elTected by a croAvd of bees Avorking in a dark hive. Granting 

 whatever instincts you please, it seems at first quite inconceiv- 

 able how they can make all the necessary angles and planes, 

 or even perceive Avhen they are correctly made. But the dilli- 



