io8 



NEEDHAM. 



[VOL. I. 



Fig. 6 is from a nymph that was fed three hours before 

 fixing. A large area (D} is discharged; groups of cells remain 



in which the discharge is yet 

 to occur. 



Fig. 7 is from the same 

 series, but shows a larger 

 area in which a very moder- 

 ate discharge is in various 

 stages of progress. The 

 forked summits of the cells 

 at the right seem to indicate 

 that the discharge in them 

 was partial. Two nuclei are 

 found not uncommonly in 

 these cells (see Figs. 4, 6, 8), 

 only one of which appears to 

 be lost at a time. 



Fig. 8 is from the same 

 series, but from a point 

 nearer the anterior end, and 

 thus represents a later stage. 

 It shows, in fact, the end of the discharge. The beginning oc- 

 curred midway between the nidi, but these last rounded globules 

 came from points nearly opposite them. The intervening cells 

 have already acquired a 

 border ; they have plenty 

 of room, are now nearly 

 cylindrical, and the 

 prominent internal folds 

 (Figs. 2, 3, 4), due to 

 later compression, have 

 not yet appeared. A 

 study of hundreds of 

 such sections shows the 

 progress of the dis- 

 charge to be about as 

 follows. The discharge begins in the anterior end of the 

 ventriculus about an hour after feeding simultaneously with 



FIG. 5. The beginning of a discharge in which the 

 left-hand portion shown is not yet involved, two 

 hours after feeding, x 275. A , a large detached 

 globule of secretion. />', smaller globules still 

 slightly connected by a slender stalk-like portion, 

 compressed between the remaining cells. 



FIG. 6. An irregular discharge found three hours after 

 feeding, x 150. The discharge is complete throughout the 

 portion D, on the point of beginning on either side. These 

 different conditions found side by side afford opportunity 

 for an interesting comparison of the state of the nidi. 



