diminished by acetylating the atoxjl. Such an acetylated atoxyl is an antipyrine wHich contains arsenious acid. Acetylated atoxyl has been shown to be of use in mice by Ehrlich, and in dogs by our experiments. We found, as a rule, that When atoxyl was given in sufficient quantity to drive out the parasites (nagana) in dogs the host was also killed, but using acetylated atoxyl we have been more or less successful. An interesting fact pointed out by Ehrlich is that the parasites can get used to a drug and become resistant. It is therefore advisable to alternate various trypanocidal agents in the treatment as much as possible, that is, to give atoxyl, some other trypanosome-killing drug, and mercury; for instance, atoxyl, fuchsin, or some other colouring matter by the mouth, and sublimate.
It has usually been recommended to give atoxyl in high doses at the beginning. Whether or not this is of benefit is a question, as the atoxyl apparently accumulates in the body, and the toxic effect appears after a time. In laboratory experiments we have frequently noticed that even after the treatment had been stopped for a week toxic effects appeared, and this could only be due to the fact that atoxyl had accumulated in the body, and the arsenic had been slowly broken up. We would like to refer to one experiment. A rat was treated about nine months ago with atoxyl and is still showing toxic effects.
We think it necessary to point out that the administration of atoxyl should be given a very careful trial, but that extremely high doses should be avoided as much as possible. The action of atoxyl seems to be very much on the nervous system, as neuritis is frequently caused by the administration of this drug. Blindness has also been observed after the use of atoxyl, and the question therefore arises whether it would not be well to counteract somewhat the effect of atoxyl by making it less operative on the brain and nerves. This might be done by introducing radicles
