WHEELER— ANT LARV^. 319 



exudate organs. If this proves to be true, the resemblance of Allo- 

 dape to Pachysima, which also rears its brood in all stages in hollow 

 stems and feeds the older larvse with food-pellets, would be very 

 striking. Allodape is also of considerable interest in connection with 

 Roubaud's observations on the wasp Synagris which will be consid- 

 ered in the sequel. 



More important in their bearing on the exudate organs of 

 Pachysima are Holmgren's observations on the termites. He de- 

 votes the twelfth chapter of his volume (1909) on the anatomy of 

 these insects to the exudate tissue. Termites are really themselves 

 physogastric like their guests, and Holmgren shows that all the 

 castes, but especially the queens, have extensive exudate tissues, 

 consisting of the peripheral layers of the abdominal fat-body. In 

 these layers the trophocytes do not contain fat-globules but nu- 

 merous minute granules which are discharged into the blood and 

 thus convert it into the exudate that passes through numerous pores 

 or lacunas in the chitinous cuticle to the surface. There it is licked 

 up by other members of the colony. He finds that the development 

 of the exudate tissue differs considerably not only' in the different 

 castes but also in their various developmental stages and 



that the intensity of the licking and feeding of the individuals of a termite 

 colony is directly proportional to the amount of their exudate tissue. Those 

 with the largest mass of exudate tissue are the best fed and the most licked. 

 In other words, the care bestowed by the workers on the various members 

 of the colony is not an immediate expression of an altruistic philoprogenitive 

 instinct (Brutpflegeinstinct), but depends essentially on egoistic motives, 

 i. e., exudate hunger. 



To this point I willingly follow Holmgren, but both he and Was- 

 mann have used their respective observations as a basis for what 

 seem to me to be rather dubious speculations, a consideration of 

 which will have to be deferred till the more general part of my dis- 

 cussion is reached. 



Escherich (1911) gives a more vivid, not to say more spectacular 

 account of the exudate hunger of termites. So eager are the 

 workers of the Ceylonese Termes rcdemanni for the exudate of 

 their huge physogastric queen that they actually tear little strips 

 out of her cuticle in order to get at the liquid more readily! 

 Escherich found that old queens sometimes have their white ab- 



