June, 1918] Parasites oj LeaJ-IIoppers 287 



owing to a lack of material, but comparisons of the later stages 

 of parasitism in these hoppers with normal individuals were 

 made. When the dryinid is in its second instar and has become 

 partly external the hypertrophied tissue has reached its maxi- 

 mum size (Plate II, Fig. 2). It is seen as a large ovoid mass 

 of cells occupying most of the body cavity in the hind thoracic 

 and anterior abdominal regions, displacing and pushing back- 

 wards the large storage stomach of the host. It extends for 

 three somities as a rule, its anterior extremity lying between the 

 muscles of the third thoracic segment. It is in intimate con- 

 nection w4th the point of attachment of the parasite. In 

 cross section the thin membrane surrounding it can be seen, 

 except at that part nearest the parasite, w^here the cells of the 

 cyst are in contact with the mouth parts of the latter, (Plate 

 IV, Fig. 3). 



In the earliest stages studied the cell walls and nuclei are 

 sharply defined and part of the tissue is composed of dividing 

 cells, (Plate IV, Fig. 2; Plate VI, Fig. 1). The cells are filled 

 with food globules and are vacuolated. Later division ceases 

 and the cells become more noticeably vacuolated, (Plate IV., 

 Figs. 3 and 4). Late in the fourth instar of the parasite dis- 

 integration of the cells begins, (Fig. 5, Plate IV, Figs. 3 and 4). 

 The cell walls are broken down, the nuclei become disintegrated 

 and the protoplasm becomes very largely filled with round 

 vacuoles. Directly after the fourth molt of the parasite this 

 cyst is attacked first and devoured after which the host viscera 

 are devoured. 



The cyst stains easily with Delafields haemotoxylin, being 

 thus sharply contrasted with the surrounding tissues which 

 take the eosin stain more readily. It reacts to stains similarly 

 and resembles fatty tissues. 



The function of such a cyst is problemmatical. It is not 

 found in a great many other insect hosts of Hymenopterous 

 parasites and has not been observed in any other genus of the 

 Anteoniyia so far. It cannot be phagocytic because the mandi- 

 bles of the parasite are not developed or are functionless until 

 the last larval molt, and it is not absorbed. Except for cyto- 

 plasmic changes it remains unchanged until the fifth instar is 

 reached by the dryinid. It doubtless serves as a means for 

 absorbing, storing up, and then in turn giving up in a modified 

 manner food for the parasite that otherwise would have been 

 utilized by the host. This food is probably absorbed from the 

 blood of the hopper through the cyst membrane. 



