THE DEVELOPMENT OF AXTS. 



69 



They not only feed, but clean and transport the young from place to 

 place, thus utilizing to the advantage of their development the ever- 

 varying temperature and humidity of the soil. By this means they 

 also protect them from exposure to light and enemies. Moreover, they 

 assist the young to undergo their transformation by embedding them 

 in the earth till the cocoons are woven, and eventually extricate the 

 hatching callows from their envelopes. This freedom in dealing with 

 the brood is certainly one of the most striking manifestations of the 

 plasticity of ants. The remarkable consequences which it entails in 

 their relations with other insects will be 

 considered in future chapters. 



As the eggs, larvae and pupae develop 

 in the dark recesses of the nest, these 

 stages are always of a pale color, usually 

 translucent white or yellowish, more rarely 

 greenish or roseate, like the corresponding 

 stages of other insects that develop in dark 

 cavities of the soil or in the tissues of 

 plants or animals. Ants rarely or never 

 bring- the brood to the surface unless they 

 feel compelled to move to another nest or 

 belong to species like the slave-makers, 

 which kidnap the young of other ants. Oc- 

 casionally, however, during very warm 

 weather, the young may be brought to the 

 surface after nightfall. In the dry deserts of 

 western Texas, I have seen Isclinoniyniic.r 

 cockerelli bring its larvae and pupae out onto 

 the large crater of the nest about 9 P. M. 

 and carry them leisurely to and fro, much as 

 human nurses wheel their charges about the 

 city parks in the cool of the evening. 



Since the brood is always nurtured in darkness we must suppose 

 that the manipulation which this implies depends on -highly developed 

 tactile and olfactory senses to the exclusion of vision. Evidence of the 

 exquisite perfection of these senses of contact-odor is seen in the segre- 

 gation of the brood according to age and condition. The eggs, larvae 



FIG. 35. Embryo of For- 

 mica gnara. (Original.) in, 

 Mandible : .r, maxilla ; /, la- 

 bium ; p l , fore leg : /> 4 , eva- 

 nescent appendage of first 

 abdominal segment ; s 1 , meso- 

 thoracic stigma ; n, nerve 

 ganglion of future ventral 

 cord ; y. yolk ; g, lateral edge 

 of germ-band which advances 

 dorsally to enclose yolk. 



and pupae of different sizes are placed in separate piles in the same or 

 different chambers of the nest, reminding one, as Lubbock ( 1894. P- 7* 

 aptly says, "of a school divided into five or six classes" (Fig. 34"). 

 Inspection of the nests of many species of ants shows that this habit 

 is very prevalent, although it is not so clearly manifested in primitive 



