44 Trypanosome causing Disease in Man in Nyasaland, 



There would appear to be little difference in the virulence of the five 

 Human strains. If any distinction be made, it might be said that probably 

 Strain I is the most and Strain V the least virulent. 



Table VII. — The Percentages of Eecoveries in Various Animals from the 

 Five Human Strains. The letter E stands for refractory. 



Strain. 



Man. 



Ox. 



Gloat and 

 sheep. 



Baboon. 



Monkey. 



Dog. 



Rabbit, 



Gruinea- 

 Pig- 



White 

 rat. 



I 







50 







E 























II 







? 





























III 







100 



























IV 







100 





























V 









. 

























It would appear to be equally impossible to separate the Human strains by 

 the percentages of recoveries. All the experimental animals, except the ox, 

 succumb to the disease if once the parasite has obtained a footing. 



Table VIII. — The Average Duration of Life, in Days, of Various Animals 

 infected with the Human Strain. The letter E stands for refractory. 





Ox. 



Goat and 

 sheep. 



Baboon. 



Monkey. 



Dog. 



Babbit, 



Gruinea- 

 Pig- 



White 

 rat. 



Average dura- 

 tion, in days 



134 



42 



E 



26 



34 



28 



67 



30 



No. of animals 

 employed 



1 



29 



1 



20 



25 



7 



15 



21 



This table shows the extreme virulence of this trypanosome for most 

 animals except the ox. The guinea-pig is somewhat refractory, and often 

 resists the first injection of infected blood, but not the second. 



Table IX. — The Percentages of Eecoveries in Various Animals infected with 

 the Five Human Strains. The letter E stands for refractory. 



J Man. 



Ox. 



Gloat and 

 sheep. 



Baboon. 



Monkey. 



Dog. 



Babbit. 



Gruinea- 

 Pig- 



White 

 rat. 



Percentages ... 







80 







E 























No. of animals 

 employed 



5 



5 



29 



1 



20 



25 



7 



15 



21 



