CELL-MAKING INSTINCT 279 



and England the slaves seem to have the exclusive care of 

 the larvae, and the masters alone go on slave-making expe- 

 ditions. In Switzerland the slaves and masters work to- 

 gether, making and bringing materials for the nest; both, 

 but chiefly 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 col- 

 lect building materials and food for themselves, their slaves 

 and larvas. 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 will, as I have seen, carry off the pupa; of 

 other species, if scattered near their nests, it is possible that 

 such pupa; 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 presence proved useful to the species which had 

 seized them — if it were more advantageous to this species 

 to capture workers than to procreate them — the habit of col- 

 lecting pupae, originally for food, might by natural selection 

 be strengthened and rendered permanent for the very dif- 

 ferent 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 than the same species in Switzerland, 

 natural selection might increase and modify the instinct — 

 always supposing each modification to be of use to the spe- 

 cies-^until an ant was formed as abjectly dependent on its 

 slaves as is the Formica rufescens. 



Cell-making instinct of the Hive-Bee. — I will not here 

 enter on minute details on this subject, but will merely give 

 an outline of the conclusions at which I have arrived. He 

 must be a dull man who can examine the exquisite structure 

 of a comb, so beautifully adapted to its end, without enthusi- 

 astic admiration. We hear from mathematicians that bees 

 have practically solved a recondite problem, and have made 

 their cells of the proper shape to hold the greatest possible 

 amount of honey, with the least possible consumption of 

 precious wax in their construction. It has been remarked 



