H4 ./ATS. 



mo>t, if iu)t all cases, highly adaptive. This is clearly seen in such 

 forms as the Judo-African Carcbara, the huge, deeply colored females 

 of which are more than a thousand times as large as the diminutive, 

 yellow workers. This ant dwells in termite nests where it occupies 

 chambers connected by means of tenuous galleries with the spacious 

 apartments of its host. The termites constitute a supply of food so 

 accessible and abundant that the workers are able to rear enormous 

 males and females, while they themselves must preserve their diminu- 

 tive stature in adaptation to their clandestine and thievish habits. Simi- 

 lar conditions are found in many species of the allied genus Solcnopsis, 

 which inhabit delicate galleries communicating with the nests of other 

 ants on the larvse and pupse of which they feed. In one species of this 

 genus (5". geminata), however, which leads an independent life and 

 feeds on miscellaneous insects and seeds, the worker caste is still 

 highly polymorphic. 



Another interesting case of adaptation in stature is seen in the 

 ants of the Formica microyyna group. The females of these species 

 are temporarily parasitic in the nests of other Formica: and are there- 

 fore relieved of the labor of digging nests for themselves and rearing 

 their first brood of larvae. On this account they need not store up 

 large quantities of food, so that the nourishment which in non-para- 

 sitic species goes to produce a comparatively few large females may 

 be applied to the production of a large number of small females. This 

 latter condition is necessary in parasitic species which are decimated 

 by many vicissitudes before they can establish themselves successfully 

 among alien hosts. I have already emphasized the adaptive significance 

 of the disappearance of the worker caste among permanently parasitic 

 species like Ancrgatcs. IV heeler iella. etc. 



There are several cases in which the worker and female differ 

 greatly in color, pilosity or sculpture, and in such cases either caste 

 may be conservative or aberrant according to ethological requirements. 

 Thus in certain temporary parasites like Formica ciliata, orcas, crinita, 

 specnlaris and difficilis, the female is aberrant in one or more of the 

 characters mentioned, while the cospecific worker retains the ancestral 

 characters of its caste in the closely allied forms of F. rnfa. The 

 same condition is seen in a very different ant, Aphcenogaster tcn- 

 nesseensis, as the result of similar parasitic habits. In all of these 

 species the females alone have developed myrmecophilous characters, 

 like the long yellow hairs of F. ciliata, or the mimetic coloring of / ; . 

 difficilis, which enable them to foist themselves on the allied species 

 and thus avoid the exhausting labor of excavating nests and rearing 

 workers. 



