PROC. ENT. SOC. WASH., VOL. 22, XO. 6, JUNE, 1920 123 



forth praise. In these prosaic days of biological facts, much of 

 the mystery of the complex social system of the ants and termites 

 which led to admiration by man has had to "go by the board." 

 Many fantastic theories have collapsed. 



One of the first of these theories to go was the instinct for the 

 care of the brood and queen. Nils Holmgren (1909), in his 

 studies of the anatomy of termites, devotes considerable space 

 to the exudate tissues. All of the castes, but especially the 

 queens, have extensive exudate tissues in the abdomen. This 

 exudate passes through pores in the chitin to the surface. Here 

 it is greedily licked up by other members of the colony. Holm- 

 gren evolved an "Exudat-theorie" to show that there is a rela- 

 tionship between the amount of exudate tissue and the care that 

 a termite received, i. e., licking and feeding. Instead of the in- 

 stinct to care for the brood, it is mere selfish desire for the exuda- 

 tion. Holmgren concludes that he regards the exudate secretion 

 not only (1) as the cause of feeding but (2) as the cause of caste 

 differentiation. The work of Miss Thompson (1917) disproves 

 Holmgren's second conclusion and also the whole subject of the 

 "manufacture" of reproductive forms through feeding by the 

 workers, so dear to students of termite biology of the eighteenth 

 and nineteenth centuries. 



" Trophallaxis" or Instinctive Behavior. According to Wheeler 

 (1918), this attribute of the parental feelings of man to insects 

 is termed "anthropomorphism" by the orthodox behaviorists. 

 In a remarkable paper on ant larvae Wheeler suggests the term 

 "trophallaxis," i. e., exchange of nourishment, for the cooperative 

 relationship between adults and larvae. Wheeler further states 



"Although considerable evidence thus points to trophallaxis as the source 

 of the social habit in wasps, ants and termites, it must be admitted that 

 the phenomenon has not been observed in the social bees." 



***** 



"If we confine our attention largely to the ants, I believe it can be shown 

 that trophallaxis, originally developed as a mutual trophic relation between 

 the mother insect and her larval brood, has expanded with the growth of 

 the colony like an ever-widening vortex till it involves, first, all the adults 

 as well as the brood and, therefore, the entire colony ; second, a great number 

 of species of alien insects that have managed to get a foothold in the nest 

 as scavengers, praedators or parasites (symphily) ; third, alien social in- 

 sects, i. e., other species of ants (social parasitism); fourth, alien insects that 

 live outside the nest and are 'milked' by the ants (trophobiosis), and fifth, 

 certain plants which are visited or sometimes partly inhabited by the ants 

 (phytophily)." 



In the termite colony the workers and young nymphs of the 



