C. DOBELL 



205 



by Werbitzki were chiefly substances belonging to the pyronin, acridin, 

 and oxazin groups (mde infra) — the best results having been obtained 



Fig. C. T. brucei, strain "nagana ferox." (1) Form without kinetonncleos, 

 after treatment with pyronin. (2) Normal form. [From Werbitzki (1910), 

 slightly diagrammatic] 



with oxazin. The action of the dye upon the Trypanosomes is rapid. 

 In one experiment in which oxazin was injected into a mouse on the 

 second day after infection with the Trypanosomes, the following ob- 

 servations were made : — 



Hours after injection 

 of dye 



1—2 



4 



6 



8 



10—12 



24 



Number of TrypanoBomes 

 without kinetonucleus 



Isolated specimens 

 10-12 7„ 

 25-30 % 

 40-50% 

 70—80 % 

 80— 90°/o 



The strain containing about 80 % of individuals devoid of a kineto- 

 nucleus, when inoculated into other mice, shows a smaller — but still large 

 — percentage of the modified organisms. By passing this strain through 

 mice 6 — 10 times, however, and treating with oxazin each time, a strain 

 of Trypanosomes in which every individual is devoid of a kinetonucleus 

 has been obtained. This strain remains constant after numerous sub- 

 sequent passages through untreated mice^ 



The Trypanosomes devoid of kinetonuclei are — as regards motility, 

 general appearance and behaviour, etc, — indistinguishable from normal 

 organisms save in this one feature. Their rate of multiplication is, 

 moreover, unchanged. They show, however, a slight difference in 

 resistance, 



^ Kndicke (1911 a) reports that one snch strain has been passed throagh 115 mice, 

 without any treatment, and still retains its morphological peculiarity unaltered, 

 Joam. of Gen, ii 15 



