108 
Haemoflagellates, etc. 
were found. All the other animals remained healthy. Kleine remarks 
that from these experiments it is seen that flies, which for many days 
after the ingestion of T. brucei were not infective, afterwards became so, 
infecting first a sheep and then an ox. Presuming that Kleine’s healthy 
animals were rigidly excluded from the bites of tsetse flies other than 
those he used, and that he was dealing with T. brucei throughout his 
experiments, it is clear that they are exactly similar to Bruce’s experiment 
No. 225 (see Appendix for confirmation of Kleine’s work by Bruce and 
his co-workers). 
On 
the 4th day 50 
flies 
fed on 
sheep No. 
3. 
99 
5th 
99 
49 
99 
99 
ox 
No. 
1 . 
99 
6th 
99 
48 
99 
99 
sheep No. 
4. 
99 
7 th 
99 
48 
99 
99 
99 
No. 
6. 
99 
8th 
99 
48 
99 
99 
99 
No. 
26. 
99 
9th 
99 
46 
99 
99 
99 
No. 
9. 
99 
10 th 
99 
40 
99 
99 
99 
No. 
10. 
99 
11th 
99 
40 
99 
99 
99 
No. 
31. 
99 
12 th 
99 
39 
99 
99 
99 
No. 
12. 
99 
13th 
99 
39 
99 
99 
99 
No. 
13. 
99 
14th 
99 
37 
99 
9 : 
99 
No. 
14. 
99 
15th 
99 
37 
99 
99 
99 
No. 
16. 
99 
16th 
99 
34 
99 
99 
99 
No. 
17. 
99 
17th 
99 
34 
99 
99 
99 
No. 
20. 
G. palpalis is therefore able to transmit T. brucei twelve days after 
feeding on an infected animal. According to Minchin and Kleine this 
would show that during this interval T. brucei had undergone a develop¬ 
mental cycle in the alimentary tract of the fly and that the infection is 
of the cyclical type. 
Kleine has however made no observations on such a developmental 
cycle in G. palpalis. It would be important in these experiments to 
ascertain whether there were any unchanged T. brucei in the alimentary 
tracts of the flies; Bruce has noted that T. brucei remains alive for five 
days in the alimentary tract of G. morsitans and its vitality appears to 
depend on the quantity of blood in the stomach of the fly. Kleine’s flies 
were fed daily so that the parasites would here have had ample nourish¬ 
ment to keep them alive. This can however only be settled by 
further observations, but it must be remembered that G. palpalis itself 
is naturally infected with two Crithidia — C. grayi and G. tullochi. 
According to Stuhlmann and Minchin T. brucei undergoes a true develop- 
