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As a result, of the above experiments it may be considered proved that the Glossina palpalis can convey the above trypanosomes from the sick to healthy animals and so propagate the disease. Apart from the great practical importance attached to this, it is also of considerable interest to note that the Glossina palpalis can convey not only the Trypanosoma gambiense, but other varieties. This being so, it is reasonable to suppose also, that other varieties of Glossina will convey the Trypanosoma gambiense. This being so, it will be evident from Mr. Austen’s map that a very extensive tract of country will be involved. At Igaga’s and Kibui, halting places of the Jinja cattle, a variety of tsetse fly ( Glossina pallidipes ) was found.
It may be, further, considered proved that (Stomoxys) cannot convey these trypanosomes from the sick to the healthy animals. This is a matter of great practical importance also, because these flies abound in Uganda.
Some observations were made on the length of time which the various trypanosomes remain active in the stomach of the fly. The contents of the stomach, food reservoirs and salivary glands have been studied both fresh and by staining, but no definite life cycle has been observed in the parasites. In the ventral food reservoir active trypanosomes have been seen up to 12 hours after feeding. This is interesting in view of the fact stated by Schau dinn, that mosquitoes discharge the contents of the sac into the wound, in fact the irritation is produced by these contents.*
Experiments were made to see whether the Glossina palpalis can convey any of these varieties of trypanosomes after longer intervals (5 days and over). These remained entirely negative. So it would appear that if the trypanosoma undergoes any transformation in the body of the fly as Schaudinn’s work suggests, it must be a short one.
A point of considerable interest in connection with the flies is the tendency which they have to “ abort ” in captivity. Mr. Austen drew attention to the great variation in size of the pupæ in some specimens sent to him and put forward the above explanation. To test this a number of pupæ have been placed in suitable places and their development noted. It was found that the small undersized specimens underwent no further alteration, whilst the larger and normal looking pupæ hatched out as usual. This would thus suggest that the small pupæ had been prematurely laid and were not viable.
APPENDIX.
In the further report, the histories of a number of cases of sleeping sickness were given ; an additional series have been
* This portion of the investigation, which is very technical, will be elaborated by Professor Minchin, who has gone to Uganda for this purpose.
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