249 
COMPARATIVE 
CHEMO-THERAPEUTICAL STUDY OF 
ATOXYL AND I'RYPANOCIDES 
PART I 
BY 
M. MERENSTEIN, Fh.D. 
J. W. GAKRErr ISrERNATIONAI. EELl.OW ANU KEi>EARCK DEMONbl RATOR OF THE 
UVERPOOI. SCHOOL OF TROFICAI. MEDICINE 
{From the Runcorn Research Laboratories') 
{Received for publication 14 May, 1908) 
Aioxyl, sodium-p-ainino phenyl-arsenate was introduced in the 
treatment of Trypanosomiasis by Thomas and BreinU (1905), and its 
specific therapeutic value for sleeping sickness has been more or ess 
recognised. It contains from 25-95 to 2078 per cent, of arsenic; the 
difference depends on the water of crystallisation, as shown by ^ oore, 
Nierenstein and Todd ^ Ehrlich and Bertheim,^ and others. 
Arsenic in the form of Atoxyl is much better tolerated by t e 
animal organism than in the form of sodium arsenate ; the therapeutic 
value of the Atoxyl. therefore, was attributed to the fact that much 
more arsenic could be administered in this new form. It was suppose 
to act simply as an internal antiseptic, and was thought to ki 
parasites in direct proportion to the amount of arsenic introduce . 
Some experiments made in June, 1907. by Breinl and Nierenstein 
seemed to disprove this idea. In an attempt to produce an active 
immunity against Ngana, mixtures of Atoxyl and trypanosomes 
mjected in different proportions, and after different periods of contact 
with the idea that by increasing the amount of trypanosome-intectea 
blood and decreasing the amount of Atoxyl, and by lessening t 
of contact, a point might be reached at which virulent trypanosomes 
could be injected with impunity. 
