causing Disease in Man in Nyasaland. 



123 



Chart 6. — Curve representing the Distribution, by Percentages, in respect to Length, of 

 500 Individuals of the Trypanosome of Naturally Infected Dog, Strain II, Dog 690, 

 taken on nine consecutive days from Rat 911. 



The curve of Strain II, Dog 690, is also eminently dimorphic, so much so 

 that the presence of two species might be suspected, one with a maximum 

 of 18 microns and the other with a maximum of 28 microns. If such were 

 the case it could be argued that in Chart 3 of Strain I the long species had 

 driven out the short. But it will be shown later that this is probably not 

 so : that the difference is merely due to dimorphism and not to the mixture 

 of two species of trypanosomes. 



Breadth. — The following table gives the breadth of Strain II, Dog 690 : — 



Table XI. — Measurements of the Breadth of the Trypanosome of Naturally 

 infected Dog, Strain II, Dog 690. 



Date. 



Experiment 

 No. 



Animal. 



Number of 

 trypanosomes 

 measured. 



In microns. 



Average 

 breadth. 



Maximum 

 breadth. 



Minimum 

 bread tb. 



1912 



911 Eat 



500 



2-79 



4 "75 



1 25 



VOL. LXXXVIII. — B. 



