TRYPANOSOMIASIS EXPEDITION TO SENEGAMBIA 
43 
Experiment C. — On March 18, 1902, a large number of Stomoxys were caught 
while feedingon a horse (Experiment LXXXVI1) infected with the human trypanosome. 
They were daily ted upon this horse, whose blood contained five parasites to a pre- 
paration until March 24. On March 25 they were allowed to bite a young non- 
infected white rat. Twenty-four flies fed well. 
The flies were then fed on alternate days on the horse and test rat as follows : — 
March 26— Flies fed on Horse LXXXVI1. Many fed. 
,, 2 7 15 5j R&t. ,, 
28 „ „ Horse LXXXVII. 
„ 29 „ Rat. 
„ 30 „ „ Horse LXXXVII. 
3 1 » » Rat - 
April 1 „ „ Horse LXXXVII. Very few fed. 
,, 2 ,, ,, Rat. Only one sucked blood. 
,, 3 ,, ,, Rat. None fed. 
,, 4 Flies were not fed. 
5 „ >, » Many dead. 
„ 6 „ „ All dead. 
This rat has been under constant observation, and up to the present no try- 
panosomes have been demonstrated in its blood. 
Experiment ON \. — Flies were caught from the same horses as in Experiment CI. 
They were placed together in a cage and allowed to feed upon Rat Experiment LXVIII, 
in whose blood there were at this time numerous ' horse trypansomes ' 
(derived originally from Horse I) ; twelve hours later they were allowed to feed upon 
a non-infected white rat. This was done on two occasions. Thirty-five flies were 
observed to feed well upon the non-infected animal. 
The experiment was commenced on April 3, and, up to the present, parasites 
have never been seen in the rat's blood. 
If the natural mode of transmission of the Gambian trypanosomes is a simple 
mechanical transference of the parasite from an infected animal to a healthy one, which 
is infected by the prick of a proboscis containing parasites, it seems strange that our 
experiments should have always been unsuccessful, and our efforts to repeat Bruce's 
transmission experiments without result. 
As has been previously said, if the parasite is transmitted in a purely mechanical 
manner, it seems probable that other insects, possessing biting parts similar to those 
of Glossina, should also be carriers of the disease.' 1 " 
* Mr. E. E. Austen, dipterist to the British Museum, who is classifying and describing the biting-flies collected by the 
expedition in Senegambia, informs us that our collection contains five species of tabanus, one species of glossina (palpalis), two of 
stomoxys, and one of lyperosia. 
In Senegal, hippoboscidae were very frequently seen, and at St. Louis we caught several blood-sucking flies which belong 
to a new genus near Musca. 
