CHAPTER V. 



THE DEVELOPMENT OF AXTS. 



" Incredibili Zropyy et ctira Eormicse educant summamque dant operam, nc 

 vel tantilltim quod spcctet eorum Vermiculorum educationem atque nutritioncm 

 omittant." Swammerdam, " Biblia Naturae," 1/37. 



'' Ces insectes, si pen timides et qui ne craignent point pour eux-memes les 

 intemperies de 1'air, sont d'une extreme sollicitude pour leur petits, ils redoutent 

 pour ces etres, d'une constitution delicate, les plus legeres variations de 1'atmos- 

 phere ; s'alarment au moindre danger qui semble les menacer, et paroissent 

 jaloux de les soustraire a nos regards." P. Huber, " Recherches sur Les Mceurs 

 des Fourmis Indigenes," 1810. 



Ants, like other metabolic, or metamorphosing insects, pass through 

 four consecutive stages, or instars, before reaching their adult, or 

 imaginal form. These stages, which are known as the egg, or embryo, 

 the larva, the semipupa, or psendonymph and the pupa, or nymph, are 

 very similar to those of other Hymenoptera both social and solitary. 

 Such close adherence to an ancient method of development in insects, 

 which, in their adult stage, present so many idiosyncrasies of struc- 

 ture and behavior, must be attributed to a general principle accord- 

 ing to which the developmental stages of an organism are much more 

 conservative than the adult. The highly modified behavior of the ants 

 themselves towards their brood certainly contrasts very forcibly with 

 the monotonous repetition in the young of stages essentially like those 

 of solitary wasps and gall-flies. This contrast becomes more intel- 

 ligible, however, when we follow the various phylogenetic stages 

 through which it has been attained. Even the solitary insects make 

 some provision for their young by placing their eggs in suitable situa- 

 tions, and while, among insects of the lower orders, these situations 

 represent merely an indefinite environment, like the earth or the water, 

 in which the young will have to seek their food, the lower Hymenop- 

 tera (saw-flies and gall-flies ) deposit their eggs only on certain plants. 

 The solitary wasps and bees make ampler provision in constructing 

 cells for the individual larvae and in supplying them directly with pre- 

 pared foods. In all of these cases the relation of parent to offspring is 

 both protective and nutritive, but the protective relation is still incom- 

 pletely developed, since these insects are unable to remove their brood 

 when the nest is disturbed or destroyed. The ants, however, have 

 entered into much more intimate relations with their progeny. They 



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