208 Dr. H. B, Fantham and Mr. J. G. Thomson. [Oct. 15, 
eyepiece. The parasites were then counted in three or four bands across 
the film, which had been previously examined in order to ascertain an even 
distribution of the parasites therein. 
ftats.—In the case of both strains if was found that the inoculated rats 
tended to fall into one of two main categories, exhibiting either ( 1) a periodic 
increase and decrease in the number of parasites in the peripheral blood (see 
Chart 1), or (2) a more or less continuous rise in the numbers of parasites 
until the animal died (see Chart 2). 
Daily counts were made of 17 rats exhibiting periodic variation, and of 
five rats exhibiting continuous increase in the case of 7. rhodesiense. Further, 
similar counts were made of seven rats exhibiting periodic variation after 
inoculation with 7’. gambiense (see Chart 3) and of four showing continuous 
increase in the case of 7. gambiense. 
[2 2345 6 Z 8 9 1011 12 13 4 15.16 17 18 19 | 
perry, Ar a a Ee) 
Teo | ea ae 
SEA Se 
Pee oe SRR See 
BRR Se 
Ea ST i 
Ree eee eRe, Ei) 
SIRES] se | 
ee ee eae ns 
id | Sea Se a 
PRA eRe ee eS 
fab Baa ee ea EA | 
a a | Sg il FN 
FP | 
(ee ee a 
9) a a ap 
Pee) ia ay eS | 
Fa aE 
scl ad ST | fs a 
yo eeeeeea ante feecee 
ueeaeee faci 'gf Sone : 
= 
Cuart 3.—Graph see Dake ants at ae Parasites, per c. mm., in the Peripheral 
Blood of a Rat inoculated with 7. gambiense. Periodic Variation. 
The average incubation period in rats in the case of 7. rhodesiense was 
2'9 days, whereas in the case of 7’. ganbiense it was 4:4 days. ‘The average 
