CELL-MAKING INSTINCT. 243 



slaves and masters work together, 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 col- 

 lect food for the community. In England the masters alone 

 usually leave the nest to collect building materials and food 

 for themselves, their slaves and larvae. 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 pupae of 

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

 such pupae 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 

 collecting pupae, originally for food, might by natural selec- 

 tion be strengthened and rendered permanent 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 than the same species in Switzerland, 

 natural selection might increase and modify the instinct — 

 always supposing each modification to be of use to the species 

 — 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 enthusiastic 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 that a skilful workman with fitting 

 tools and measures, would find it very difficult to make cells 

 of wax of the true form, though this is effected by a crowd 

 of bees working in a dark hive. Granting whatever in- 



