366 Transactions of the Canadian Institute [vol. ix 



no tests have been made, but the observations of Weidel''^ point con- 

 clusively in this direction. He noted that the walls of the protective 

 sheath become delignified; this is strongly suggestive of the presence of 

 a hadromase or allied ferment. 



With the purpose of discovering the source of the enzyme a 

 number of species of Cynipid larvae were examined for glandular 

 structures. An enlargement of the first two segments immediately 

 below the mouth was found to be a common characteristic of all these 

 specimens. Regularly arranged on these projections are two pairs of 

 openings as shown in Text Fig. 8. Longitudinal serial sections of 

 Philonix nigra Gillette and Amphibolips confluens Harris show that 

 these openings are connected by ducts with cavities lined by a glandular 

 epithelium .composed of large cells. From these cells the enzyme 

 containing material passes into the cavity and from thence to the 

 outside by means of the duct. There seems little reason to doubt but 

 that these structures are salivary glands opening externally, and that 

 they are the source of the enzyme. A gland with the connecting duct 

 is shown in Text Fig. 9. Only the two species mentioned have been 

 examined by serial longitudinal sections, but the external openings were 

 noted in several forms and in all probability these glands are a 

 characteristic common to all the Cynipidse. 



Fig. 8. — Head of Cynipid larva 8howing external openings i'ig. 9. — Longitudinal section of the larva 



of the salivary glands just below the mouth. of Philonix nigra Gillette, passing through 



a salivary gland and its associated duct. 



Concerning the feeding habits of the larvae of the Cynipidse, we can 

 state positively that the cell contents alone furnish the nourishment and 

 that these are withdrawn from the cells without destroying the walls. 

 An enzyme secreted by the salivary glands of the larva partially pre- 

 digests this food. This ferment must act through the *cell membrane 



*I have found that the froth on plants in which the "Spittle Insects" of the 

 Family Cercopidae develop, also contains an enzyme that rapidly changes starch to 

 sugar. Experiments by Miss J. McFarlane that are not yet fully completed seem to 

 indicate a larger amount of sugar in the stems surrounded by the froth than in 

 corresponding parts of unaffected stems. 



