168 



Dr. H. L. Duke. 



[Feb. 26, 



A free portion is always discernible in the flagellum, though, in the case 

 of the stumpy forms, it is often extremely short. 



Movement. — No marked translation ; remains actively wriggling in one 

 spot, making occasional short gliding excursions about the field. Often the 

 side-to-side movements are of a jerky character. 



These experiments though few in number afford valuable evidence in 

 favour of T. gambiense to the exclusion of T. brucei. The sub-chronic type of 

 the disease in rats is perhaps the most striking point in the above table. 



Action of Human Serum. — The assumption that T. brucei is non-pathogenic 

 to man rests chiefly on the susceptibility of this trypanosome to human 

 serum. Laveran and Mesnil,* in describing the action of this serum on 

 animals infected with T. brucei, confine their attention chiefly to rats. The 

 following experiments in which animals suffering from the Damba trypanosome 

 were treated with human serum may now be considered : — 



Animal. 



Ultimate source 

 of virus. 



Quantity 



of 

 human 



Native 

 sup- 

 plying 



Condi- 

 tion of 

 blood 

 at time 



Day after inoculation. 





inocula- 

 ted. 



of 

 lation. 



1st 



2nd 



3rd 



4th 



5th 



6th 



7th 



8th 



9th 



10th 



Monkey 401 



Situtunga 402-3 



% 



B. 





1 seen 





















„ 511 

 „ 391 



509-10 

 Human strain ... 



3^ 

 3 



Y. 

 Y. 



+ + 



1 seen 





- 











1 seen 





j 



+ + 



Eat 477 ... 



„ 576 ... 

 Monkey 563 



Situtunga 402-3 

 Wild lake flies ... 



1 

 1 



3£ 



Y. 



Y. 

 Y. 



+ + + 

 + + 









+ + 



+ 



+ + + 



+ + 









Remarks. — It will be seen that in every case where the human serum was injected into a monkey the trypanosomes 



disappeared from the circulation for a longer or shorter period. In the case of the rats this did not occur. It would 

 thus appear that there is some condition present in monkeys which causes them to react to human serum, this 

 condition not being present in rats. Experiments conducted in vitro on the same lines appear to confirm this 

 conclusion. The negative results obtained with Eats 477 and 576, together with the positive result obtained with 

 the human strain in Monkey 391, neutralises what at first appeared evidence in favour of T. brucei. 



As regards the diagnosis of the three species of trypanosomes described in 

 Goat 512 (Table V), the following methods were employed : — 



(1) Examination of fresh blood preparations. 



By this means T. uniforme was identified in the blood of Situtunga 510, 

 and in the case of Goat 512 all three species were recognisable. 



(2) Examination of stained films. 



T. uniforme identified in blood of Situtunga 510. 



maxim., 19'00 /x; minim., 14 - 5 /j. ; average, 15 - 9 /j. (dry fixation). 

 * Laveran and Mesnil, ' Trypanosomes et Trypanosomiasis,' 1904. 



