Experimental Treatment of Trypanosomiasis. 141 
not certain what happens: but in rabbits stained films of blood, taken at 
various intervals after the intravenous administration of the metal, seem 
to show that the leucocytes go on taking up the particles until they can 
contain no more, and then disintegrate at varying periods afterwards, thus 
providing a constant, though small, supply of antimony. The disintegration 
would seem to be due to the destruction of the leucocytes by the antimony 
they have taken up, but on the other hand, many of the leucocytes which 
have not taken up too much appear to be quite healthy. We have found 
that both cerebro-spinal fluid and blood serum are, as far as a solution 
of any trypanocidal substances is concerned, by themselves quite without 
action on metallic antimony, even when kept in contact with it for periods 
up to three days. Experiments were undertaken with these fluids after 
their contact with the metal both on infected animals and upon trypano- 
somes 7m vitro with entirely negative results. 
The time at which no more particles can be found in, or in which they 
disappear from, the leucocytes, varies in the different animals; in rabbits 
they can be found for three or four days; in horses we have not found them 
after three days ; and in dogs not after two. 
Sufficient soluble antimony is formed in all these animals after an 
appropriate dose of the metal to drive the trypanosomes out of the 
peripheral blood in about 24 hours; that is, more than double the time 
taken by the soluble salts to attain the same result. 
We have not had in rabbits, dogs, or horses any plugging of capillaries 
with the metal, but the animals appear to be more sensitive to over-dosage 
with the metal than with the salts. Testing the dosage on healthy 
uninoculated animals is also fallacious, as a fatal dose to a healthy animal 
is apparently borne well by a similar animal when its blood is full of 
trypanosomes; we believe, also, that in the same animal a large dose is 
better borne when the blood contains trypanosomes than when it is free. 
When antimony in this form is prepared in larger quantities, it becomes 
more difficult to remove impurities from it. We mention this as we have 
had deaths from doses which had previously been well borne, which we 
attribute to these impurities, but these difficulties are now overcome. 
Of the 26 dogs treated with antimony, the details of which are given 
in the last Report, one (No. 1) lived for over 15 months in good condition, 
and was then killed. Inoculations from all the organs into rats proved 
negative, and the animal was regarded as cured; twelve others (Nos. 2, 
5, 7, 9, 10, 11, 13, 14, 16, 17, 18, 19), which lived for from 48 to 94 days, if 
inoculation into rats from the organs after death can be accepted when 
negative as evidence of cure, may also be regarded as cured. 
VOL. LXXXIII.—B. M 
