LOE 2% Messrs. H. G. Plimmer and J. D. Thomson. [Oct. 28, 
Sodium Arsenyl Tartrate or Sodiwm Tartrarsenite—This compound was 
investigated by Henderson and Ewing* in 1895, who gave it the formula 
AsONaC,H,0¢.24H20. 
It was prepared for these experiments by dissolving one equivalent of 
arsenious oxide in two equivalents of acid sodium tartrate, filtering, 
evaporating to a small volume, and adding alcohol till crystallisation 
commenced ; on cooling, the substance crystallised out. 
This substance does not seem to be anything like so effective as the 
antimony compound. Of five rats which have been treated with it, four died 
between the 12th and 24th days, and three of these had a recurrence; one is 
still living on the 21st day, but we think that this is probably due to the 
sodium antimony] tartrate which was given after a recurrence, in the same 
way as if from the beginning of the disease. 
A mixture of equal parts of a 1 per cent. solution of sodium antimonyl 
tartrate and of sodium arsenyl tartrate has been tried on six rats. One died 
on the 14th day and the five others are still living on the 21st day without 
any recurrence. 
Immunity. 
With a view of ascertaining what amount of immunity, if any, had been 
conferred on an animal which we considered to be cured, a Nagana rat was 
taken which was inoculated on May 13, and had been afterwards successfully 
treated with atoxyl and succinimide of mercury, and in which no trypano- 
somes had been found since it had its first dose on May 16, when the 
trypanosomes were very plentiful in the blood. On October 7, the 147th 
day, the rat was re-inoculated from another Nagana rat, and on the 11th 
trypanosomes were present in numbers in the blood; a dose of sodium 
antimony! tartrate was given and no trypanosomes have been seen since the 
12th. This seems to point to the fact that no immunity is conferred. 
DESCRIPTION OF PLATE. 
The microphotographs were made from rough blood-preparations, with a low-power 
objective (Zeiss 8 mm.), in order to demonstrate the rapid disappearance of the trypano- 
somes from the blood after administration of sodium antimonyl tartrate. 
Fie. 1 shows the blood of a Nagana rat, 4 days after inoculation, before treatment. 
Fic. 2 shows the blood from the same rat half an hour after the injection of 0°35 c.c. of a 
1 per cent. solution of sodium antimony]! tartrate. 
Fic. 3 shows the blood from the same rat one hour after administration of the above dose 
* Henderson and Ewing, ‘Chem. Soc. Trans.,’ 1895, vol. 67, p. 103. 
