530 Sir D. Bruce and others. Description of a 



the salivary glands swarming with trypanosomes. Parts of these glands 

 injected into Eats 2311 and 2312 gave in both cases a positive result. 



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







Proboscis. 

















Time, 

 days. 







Proventri- 

 culus. 





Fore- 

 gut. 



Mid- 

 gut. 



Hind- 

 gut. 



Salivary 

 glands. 



Expt. 



Labial 

 cavity. 



Hypo- 

 pharynx. 



Crop. 



1857 



62 







- 







+ 







1996 



23 











+ + 



+ + 



+ + 





1996 



43 











+ 



+ 



+ 





1996 



57 











+ + 



+ + 



+ + 





1996 



57 













+ + 







2111 



12 













+ 



+ 





2111 



29 





_ 



+ 



+ 



+ + 



+ + 



+ + 





2111 



40 













+ 







2188 



21 













+ 



+ 



1 



In none of the negative experiments was an infection of the salivary 

 glands found. Nine infected flies were dissected, but not one of these had 

 passed into the infective stage. No parasites were found in the proboscis at 

 any time. 



From a consideration of these tables it will be seen that this strain of 

 T. brucei, Zululand, 1913, belongs to the same group as T. gambiense and 

 the trypanosome causing disease in man in Nyasaland as far as their 

 development in G. palpalis and G. morsitans is concerned. This develop- 

 ment takes place in the intestine of the fly and, after a varying number of 

 days, passes forward into the salivary glands, where the final stage in the 

 cycle is reached — the infective or " blood forms." In this group the 

 parasites are never found fixed in the labial cavity as in the pecorum and 

 vivax groups. 



The Type of Trypanosome pound in the Infected Flies. 



Plate 25 represents the developmental forms of T. brucei, Zululand, 1913, 

 found in the proventriculus and salivary glands of G. morsitans. A descrip- 

 tion of the various types found in the different parts of the alimentary tract 

 is not considered necessary, as they are identical with those found in the 

 development of T. gambiense in G. palpalis, which have already been fully 

 described.* 



Figs. 1 and 2 are two long trypanosomes from the proventriculus. 

 Figs. 3-6 are the same, but they were extruded on to a cover-glass by 

 * 'Koy. Soc. Proc.,' B, vol. 83 (1911). 



