TREATMENT OF TRYPANOSOMIASIS. 33 



this reason both sickly and robust monkeys were arranged in each group, 

 receiving the same dose of the drug. The strain of trypanosoma em- 

 ployed for inoculating the monkeys of this series was a virulent one, 

 originally obtained from a native pony which showed well-marked symp- 

 toms of surra; it had been passed successively through 2 horses, 1 'monkey, 

 and then through a third horse before being employed in these experi- 

 ments. No attempt was made to treat any of these "passage" animals 

 until after the strain of surra had been passed to the next host, and hence 

 the trypanosomata, when inoculated into the monkeys of this series, had 

 never been in contact with arsenic. 



About 3 cubic centimeters of the blood of the last "passage" horse, in which 

 the trypanosomata were fairly numerous, were suspended in 100 cubic centimeters 

 of salt solution, and 2 cubic centimeters of the suspension were inoculated sub- 

 cutaneously into each of the 20 monkeys on July 8, 1909. On July 12, 1909, 

 a blood examination proved to be positive in nearly every instance, and on July 

 13, when the treatment was begun, trypanosomata were present in the blood of 

 all the monkeys, being very numerous in most instances. 



Two of the monkeys of the series were left untreated to serve as controls, 

 and these died, one seventeen and the other fourteen days after inoculation. 

 Monkey No. 4293, which had been in captivity at the laboratory for a long time, 

 was found dead on the third day after inoculation. 



The arsenophenylglycin was administered subcutaneously in doses varying from 

 0.04 to 0.09 gram per kilo of body weight. Monkeys Nos. 4332 and 4341 were 

 animals which had been employed previously for other experiments and were in 

 poor condition at the time of the present experiment; the former died in eight 

 days, the latter in five days after the treatment, death being due, in our opinion, 

 to the combined effect of exhaustion from prolonged captivity and the surra 

 infection and to the toxic effect of the drug. The results obtained with these 

 2 monkeys should be disregarded. 



"With these exceptions, it is seen from Table II that every monkey 

 receiving an injection of 0.06 gram per kilo or less showed a relapse of 

 the infection after an interval of from eighteen to fifty-five days. As 

 soon as they were found to have suffered a relapse, all of the monkeys 

 with the exception of No. 4421, were given a second dose of 0.08 gram 

 of arsenophenylglycin per kilo. With the exception of monkey Xo. 4473, 

 which died within four days after the second injection, all were, we 

 believe, permanently cured. Two are still alive seven months after the 

 second treatment. Many have become somewhat weak and emaciated 

 from their long confinement in small cages. However, the emaciation 

 was not due to a relapse of the surra infection which remained undis- 

 covered, as was shown by the following observation : 



Three of the treated monkeys (Nos. 4479, 4476, and 4481) which were so 

 thin and weak that it was obvious they could live under existing conditions only 

 for a few weeks longer, were taken on November 11, 1909, to the residence of 

 one of us and kept in the open air on a chain. They all quickly began to gain 

 in strength. One died a few weeks later after having been exposed to wind and 

 rain. The other two gained in weight and strength and are still alive. 

 94620 3 



