1919] Chalcid-fly Parasitic on Ant 19 



organs. But if such were the case it seems impossible to point 

 out any way in which they might bear any relation to the host. 

 It is of course possible that neither of the foregoing suppositions 

 is true, and that the apparent exudatoria or blood spaces between 

 the body and integument are simply adaptations to assist 

 in ecdysis. Such can hardly be the case however, as they do 

 not exist in other parasitic Hymenoptera with habits similar 

 to those of Perilampus and in which ecdysis must be undergone 

 under the same conditions. 



None of these suppositions seems adequately to explain 

 the structure of the Perilampus larva and pupa, and unless the 

 exudatoria are functionless their presence must be due to some 

 other cause. It is barely possible that they may bear a relation 

 to the host other than those enumerated above. 



It is known that the larvae or many if not all externally 

 feeding parasitic Hymenoptera secrete a salivary liquid which is 

 injected into the host. This contains digestive enzymes which 

 act upon the tissues to induce extra-intestinal digestion and a 

 consequent liquefaction of the food material which is then more 

 readily ingested. In ants at least, as has been pointed out by 

 Wheeler (1918) there are undoubtedly cases where such secre- 

 tions have both a digestive and exudatorial function. With this 

 in mind it is possible that the secretion which is actually pro- 

 duced on the surface of the body of the Perilampus larva 

 {vide Smith 1912, p. 50) may have a digestive function. With 

 this hypothesis there is one difficulty; only a small part of this 

 secretion could possibly enter the wound caused by the feeding 

 larva in the host. 



Of all these conflicting suppositions none appears satis- 

 factorily to explain the conditions as they occur in Perilampus, 

 and it is perhaps more likely that the exudatoria may have 

 been present in the common ancestors of both Perilampidce and 

 Eucharidas. If such be true, they have persisted in both 

 families and have in the Eucharidas assumed a secondary 

 function; as their exudates have proved to be attractive to the 

 ants upon which they are. parasitic. We may then believe that 

 they, ;were originally either secretory or excretory organs, 

 or those assisting in some way in the process of ecdysis 



Tublsrcular excrescences of somewhat similar appearances 

 are to be seen in .many larval insects of very diverse groups, 

 e. g.., inv'many caterpillars, in certain parasitic beetles, in one 



