causing Disease in Man in Nyasaland. 



523 



In the last Experiment, 1729, there was also only one infected fly found. 

 The salivary glands were swarming with trypanosomes. 



The next table gives the result of the dissection of the infected flies found 

 in the experiments which remained negative. 



In the negative Experiments 563, 1560, and 1710, none of the flies were 

 found to be infected with trypanosomes in any part (see Table I). These 

 experiments are therefore omitted from this table. 



Table VII. — Laboratory-bred Flies. Eesult of the Dissection of the Infected 

 Flies found in the Negative Experiments. 



Expt. 



Time, 

 days. 



Proboscis. 



Proventri- 

 cuius. 



Fore- 

 gut, 



Mid- 

 gut. 



Hind- 

 gut. 



Procto- 

 deum. 



Salivary 

 glands. 



668 



42 







+ 



+ 



+ 







879 



7 







+ 



+ 



+ 







879 



8 







+ 



+ + 









879 



9 







+ 



+ 









879 



11 









+ 









879 



24 





+ 



+ 



+ 



+ 







879 



28 





+ + 



+ + 



+ + 



¥ + 







879 



40 





+ + 



+ + 



+ + 



+ 







1072 



7 







+ 





+ 







1072 



10 







+ 



X 



+ 







1072 



38 





+ + 



+ + 



+ + 



+ + 





+ + 



1494 



7 





+ + 













1494 



17 







+ 



+ 









1494 



31 







+ 



+ 









1686 



8 







+ + 



+ + 



+ 







1686 



26 







+ 



+ 



+ 







From these negative experiments it will be seen that only in one fly did an 

 infection of salivary glands occur. Why this fly did not infect the animal it 

 fed on is impossible to say. 



The Methods used in the Examination of the Flies. 



The flies were dissected as described in a previous paper.* As each fly in 

 a cage died it was dissected, and the result, as regards the presence of 

 trypanosomes in the alimentary tract and salivary glands, recorded. Fixed 

 and stained preparations were then made from the various parts and numerous 

 drawings of the various types of trypanosomes encountered were made. The 

 method described in a previous paperf of isolating infective flies and inducing 

 them to salivate on clean cover-glasses was also made use of. This is a useful, 

 simple and practical method, as it demonstrates clearly the type of trypano- 

 some thrown out from the tip of the proboscis when the fly feeds. 



* 'Roy. Soc. Proc.,' B, vol. 83, p. 513 (1911). 

 t Ibid., B, vol. 87, p. 63 (1913). 



