36 



Sir D. Bruce and others. 



Trypanosome 



after the importance of the hypopharynx became evident that an examination 

 of these separate parts of the proboscis was made. 



In Experiment 546 only one infective fly was found In Experiment 524 

 two infected flies were found ; in one of these the development wa,s incom- 

 plete, in the other complete. In 1737 two flies were infective, in 1853 three, 

 and in 1950 four. In not a single fly was any invasion of the salivary glands 

 noted. 



The following Table gives the result of the dissection of the infected flies 

 in the negative experiments : — 



Table V. — Laboratory-bred Flies. Negative Experiments. 







Proboscis. 



. 















Time, 

 days. 







Proventri- 

 culus. 





Fore- 

 gut. 



Mid- 

 gut. 



Hind- 

 gut. 



Sulivary 

 glands. 



Expb. 







Labial 

 cavity. 



Hypo- 

 pharynx. 



Crop. 



2115 

 2115 

 2115 

 2115 



9 

 9 

 9 

 11 



+ 





+ 

 + 





+ 

 + 



+ 

 + + 

 + + 

 + + 



+ + 

 + 





In the negative Experiment 1732 all the flies were found to be negative. 



In Experiment 2115 four infected flies were found, but in none of these 

 had the development reached the hypopharynx ; none of them were infective. 

 : From a consideration of these tables it will be seen that T. pecorum 

 belongs to the same group as T. simice as regards its development in 

 (r. morsitans. This development takes place at first in the intestine, then 

 passes forward into the labial cavity, and finally invades the hypopharynx 

 and there is completed. 



The Type of Trypanosomes Found in the Infected Flies. 

 Plate 2 represents the developmental forms of T. pecorum in G. morsitans. 

 In regard to the forms found in the intestine, it may be said that these are 

 indistinguishable from the developmental forms of other pathogenic trypano- 

 somes, and what was written in regard to T. simice* is equally applicable to 

 T. pecorum. 



Figs. 1 and 2 are forms from the proventriculus, and represent the dominant 

 intestinal trypanosome forms passing forward to the labial cavity. 



Figs. 3-8 represent early forms found in the labial cavity. These were 

 seen adhering singly by their flagella to the labrum. 



* ' Eoy. Soc. Proc.,' B, vol. -87, p. 65 (1913). 



