402 Miscellaneous. 



examinations giving positive results, subsequent examinations yield 

 negative results ; but at the end of a month or six weeks the 

 Trypanosomes have established themselves in the blood, and their 

 number is, in general, large enough to enable the action of medica- 

 ments to be readily observed ; and this is the time to be chosen for 

 experiments with drugs and serums. 



Fresh serum of guinea-pig, sheep, and horse proved without 

 action upon Tr. gamhiense, like humai] serum ; this was to be ex- 

 pected, because the guinea-pig, sheep, and horse can alike be infected 

 with Tr. gamhiense. 



P. Manson tried the treatment of a case of injection by Trypano- 

 soma with injections of horse serum, but failed (Brit. Med. Journ. 

 30 May, 1903) ; the result might have been foreseen, the horse not 

 being refractory to infection by Tr. gamhiense (Button and Todd, 

 1st Rep. of the Trypanosomiasis Exped. to Senegambia, 1902, 

 Liverpool, ]903, exper. 87, pi. x.). 



This Trypanosome develops unfortunately in the blood of most 

 mammals. I ought, however, to saj^ that the serum of a Cyno- 

 cephalus, apparentl}' naturally immune against Tr. gamhiense, 

 showed itself as little active as the serum of animals having an 

 admitted susceptibility to this Trypanosome. 



It will be well to experiment with the serum of animals with 

 acquired immunity against Tr. gamhiense and that of animals 

 made hyper-immune, but the results of previous researches in this 

 direction with other pathogenic Trypanosomes (Laveran and Mesnil, 

 " Ilecherches sur le traitement et la prevention du Nagana," Ann. 

 de I'Instit. Pasteur, Nov. 1902), aud of some trials of the curative 

 power of serum of animals with acquired immunitj' against Tr. 

 gamhiense itself, leave but small hope of a definitive result of such 

 experiments. 



Human serum, inactive against Tr. gamhiense, has, on the con- 

 trary, an evident though feeble action on the Trypanosoma of horses 

 in the Gambia. It is now demonstrated that this latter Trypano- 

 some must be completely separated from Tr. gamhiense, from which 

 it is distinguished by its morphological characters, as well as by its 

 pathogenic action on animals ; but at the outset of their researches 

 Button and Todd have placed the question of the identity or non- 

 identity of these parasites observed in the same region. Their 

 different reaction with human serum provides a fresh proof in 

 support of their differentiation. Human serum injected in suffi- 

 ciently large doses into mice and rats having a fair number of the 

 Gambia horse Trypanosomes in their blood, generally causes these 

 Trypanosomes to disappear in 36 or 48 hours ; but the parasites 

 do not fail to return. 



In the cases where the Trypanosomes are numerous, the injection 

 of human serum can only have for result a diminution of their 

 number. The activity of human serum is, in short, real but more 

 feeble than in the case of Nagana, Surra, and Caderas. 



Arsenious acid is the only drug which has given any favourable 

 results in the treatment of Surra and Nagana {op. cii., Ann. de 



