DIVISION OF LABOUR. 23 



state of imperfection, that some neuters shall exhibit 

 characters at variance with those of the common kind.' 

 This, indeed, credits them with a very remarkable 

 instinct, and yet I see no more probable mode of ac- 

 counting for the facts. Moreover, the exact mode by 

 which the differences are produced is still entirely 

 unknown. 



M. Forel, in his excellent work on ants, has pointed 

 out that very young ants devote themselves at first to 

 the care of the larvae and pupae, and that they take no 

 share in the defence of the nest or other out-of-door 

 work until they are some days old. This seems natural, 

 because at first their skin is comparatively soft ; and it 

 would clearly be undesirable for them to undertake rough 

 work or run into danger until their armour had had 

 time to harden. There are, however, reasons for think- 

 ing that the division of labour is carried still further. I 

 do not allude merely to those cases in which there are 

 completely different kinds of workers, but even to the 

 ordinary workers. In L. flaviis, for instance, it seems 

 probable that the duties of the small workers are 

 somewhat different from those of the large ones, 

 though no such division of labour has yet been detected. 

 I shall have to record some further observations point- 

 ing in the same direction. 



The nests of ants may be divided into several 

 classes. Some species, such as our common Horse ant 

 {Formica rufa), collect large quantities of materials, 

 such as bits of stick, fir leaves, &c., which they heap 



