PARASITES OF FLIES 



237 



The fonnation of the flageUum in Herpelomoiias inttscie-doinestica; is preceded Ijy the 

 development of what appears to be a vacuole close to the blepharoplast, later the 

 flagellum is seen lying in the vacuole, and when the vacuole ruptures it is extruded." 

 The flagellate stages are found in the mid- and hind-guts of the adult insects. The 

 post-flagellate stages are passed in the rectum. "The flagellates become attached to 

 the intestinal epithelium, divide more than once, and at the same time the free portions 





Fig. 28. Preflageliate stages of Hc7-petonioiias calliphoviF in the crop of a fly. 



1-2. Non-dividing forms ; the nuclear karyosome shown in Fig. i was stained blue 

 with Giemsa's stain. 3-4. Dividing forms ; in Fig. 4 a pseudo-mitotic division 

 of the blepharoplast. 5. Degenerated preflageliate ; the nucleus has disappeared. 

 6-7. Forms with a short external flagellum. 



Fig. 29. 1-3. Preflageliate forms of Herpetonionas cal/ipkorie in the mid-gut. 

 4. Transitional stage towards the formation of a lull-grown Herpetomonas. 



of the flagellum become detached while the intracellular portion is absorbed. The 

 parasites then become encysted and are attached loosely in masses to the rectal 

 epithelium. The cysts are passed out in the faeces of the insects and again ingested." 

 "I have had the opportunity of studying the flagellate in the house-fly and am 

 unable to confirm Prowazek's view of its flagellar apparatus (who thought it had a 

 double flagellum) ; in order to settle this point I carried out a numlser of feeding 



