METAZOA INSECTA. 407 



after the metamorphosis which is the only instance known 

 among insects. This growth does not affect the chitinous 

 segments which are close together before egg-bearing 

 begins, and afterward far apart (PL 983, fig. 4; see also 

 PL 988, fig. 2). 



Besides the young and the winged and, later in life, the 

 wingless males and females, there are workers and 

 soldiers in the colony of T.lucifugns. The larvae which 

 produce these different forms are all alike, and it is prob- 

 able that the duties which have devolved upon certain 

 members of the colony, generation after generation, have 

 been one cause of the loss of wings. The more immediate 

 cause lies in the physical condition of food which is of 

 such a nature as to divert the larvae from the usual 

 course of development and to equip the adults for a spe- 

 cial work. 



Although the worker of Termes (PI. 983, fig. 6 ; No. 

 991) is apparently more like the larva than the winged 

 insects, yet in reality it is farther removed from the larval 

 form, since its ancestors were doubtless winged creatures 

 whose descendants gradually lost their wings by ceasing 

 to fly, and by becoming laborers for the colony in the way 

 of building and repairing nests, storing food, feeding the 

 young, etc. In doing this work they have become more 

 hardy and are provided with dark-colored mandibles and 

 feet. 



Still greater specialization along the same line results 

 in the termite soldier (PI. 983, fig. 7 ; No. 992). Its 

 head is immense for so small a body, and all its parts are 

 more or less modified. The mandibles are powerful and 

 the whole organization is that of a fighter. 



According to the view just stated the worker and 

 soldier are termites which have come to their present con- 

 dition by a process of specialization, and are not illustra- 

 tions of arrested development as maintained by some 

 naturalists. If they were such illustrations, they might 

 be placed side by side with the larvae. But, on the con- 



