Social Insects. 73 



also used for food has been shown by Grass! and others, while the tendency 

 to feed freely upon one another is matter of common record, and indeed all 

 the dead and dying are devoured.* 



In Calotermes the excrement consists of dry and hard sub-ovoid particles 

 which accumulate in the burrows, so that the faeces are not used here 

 whether as food or to line the burrows. Consequently the young must de 

 pend entirely on liquid from the mouths of the females. The food is, how 

 ever, from what has gone before, sufficiently varied in those species which 

 exhibit the greatest number of colony forms, to justify the belief, here set 

 forth, that it has much to do in the development of those forms. 



It is, however, definitely known that differentiation of the sexes takes 

 place at an early period, and can be recognized by anatomical and exter 

 nal characters in the larva, immediately after the first moult. Freshly 

 hatched larvae appear to be sexually undifferentiated, although it is probable, 

 as suggested by Newman in 1853 and Hagen in 1855, that this is simply be 

 cause the differences are too minute to be observed. Sex is doubtless de 

 termined in the egg, but the different forms of either sex are, in all proba 

 bility, due to food and treatment in the first larval stage, and to an innate 

 tendency confirmed by heredity. The mode of treatment of the mother, in 

 insects generally, may influence the sex of the offspring; but there is no evi 

 dence to show that the sex can be altered when the egg has once passed. 

 Fecundity varies in individuals of any community, and a certain number 

 are always sterile. In the social insects this condition is simply controlled 

 to the advantage of the species, and the tendency, associated with various 

 other modifications, has been emphasized by heredity. Prof. B. Grassi 

 (Bull. Mensuel Acad. Gioenia, 1889; Entom. Nachrichten, 1889) has of 

 fered a rather curious explanation of the origin of the sex in Termites. He 

 finds in the ccecum of the young larvae, as well as in the fully developed 

 workers and soldiers, an abundance of protozoon parasites. With each 

 moult these parasites disappear, but immediately commence to reappear, 

 and the ccecum is inflated in a sac which presses on the sexual organs so 

 that the development of the latter is prevented, the protozoons not appear 

 ing, after the first moult, in those individuals which are to become truly 

 sexual, or at least in only the smallest quantities. He bases this view upon 

 the examination of many hundreds of individuals, but the probabilities are 

 tiiat the presence of the protozoons has no essential part in the result, as he 

 offers no explanation as to why they are absent or less numerous in the one 

 case than in the other. 



COMPOSITION OF THK TERMES COLONY. Remembering that in Termes the 

 adolescent stages actively participate in the work and composition of the 

 colony, and accepting the nomenclature most recently used by the latest 

 and best observers, the forms already indicated in the diagram on p. 33 

 may be enumerated as occurring in the species of the genus Termes, as ex 

 emplified by the commoner European and American species: 



Prof. Grassi has enumerated some three additional forms, but this con 

 fusing complexity of forms really occurs only among those which are re 

 productive and they never all occur at one and the same time, while some 

 of them only occur under certain peculiar conditions. 



The youngest larvae, i. e., the indistinguishable freshly hatched larvae of 

 all forms (No. 1) are very small, in no species attaining 2 mm. in length. 

 They are delicate, feebly chitinized creatures, blind, the thoracic segments 

 not specialized, and with short 9-to 10-jointed antennae. After the first 

 moult the differentiation into neuters and sexed individuals becomes appre 

 ciable, not only in the beginnings of the development of the sexual organs, 

 but in the increase in the number of an tennal joints. The larvae and sub- 



*By placing a small quantity of arsenic or calomel mixed with sugar in their burrows 

 or nests, the termites will greedily devour the mixture, and by means of the poisoned 

 individuals being fed on as fast as they perish, the whole colony will in time be de 

 stroyed. 



