255 
when combined with the tissues, Atoxyl acts as a storage for effective 
arsenic 
This, however, is apparently not the case. It is well known that 
Tnpanred, Afridol blue and Afridol violet, also Parafuchsin, have an 
effect on trypanosomes comparable to that of Atoxyl. These 
compounds do not contain arsenic, but a large number of amido 
groups. Further. LaveranA also Thomas and Breinl, have found that 
sodium arsenate in combination with trypanred acts much better than 
sodium arsenate alone. 
We have, therefore, reason to believe that the amido group in 
Atoxyl, and in the above-mentioned colouring matters, has a specific 
action on trypanosomes, and that in Atoxyl the effective part is not 
only the arsenic, but also the amido group. 
How this group acts on the parasites is engaging our attention at 
present, and will form the subject of a subsequent communication. 
literature 
Moork. Nterknstkin Axn Tonn. Rio-( liemical J”'”’"'*'’ ^ P 3 - ' 
3' Ehrlich and Bkrthkim. Ber. d. deutsclien chem. Gesel'schaft, \ol. { 3 
(1007). 
4- Uhles’hoth, Huhnkr and WoiTHE. Arbeiten aus 
amte, p. 256, 1907. 
I 
8. Laveran. C. R. de I'Acad. des Sciences, Vol. CXL. p. io8, 17 April. IQO^. 
