Miscellaneous. 403 



l'lnst. Pasteur, Nov. 1902) ; it was therefore of interest to experi- 

 ment on its efficacy against Tr. gambiense. 



It results from experiments which I have made on rats that 

 arsenious acid, given in sufficient doses, causes the Tr. gambiense to 

 disappear from the greater circulation, at least in a temporary 

 manner, and that it can hasten the cure of Trypanosomiasis in these 

 animals. The efficacious dose is Ol mgr. of arsenious acid for 

 every 20 grm. of animal, i. e. 1 mgr. for a rat of 200 grm. ; helow 

 this dose the results are nil or incomplete. 



(Note. — This is also the efficacious dose in Nagana, Surra, and 

 Caderas. The solution employed for hypodermic injection has the 

 following composition : — Arsenious acid 1 grm., carbonate of soda 

 1 grm., distilled water 500 grm. — Laveran and Mesnil, op. cit.) 



In human Trypanosomiasis arsenical compounds have been often 

 tried and have yielded only a passing amelioration, but in general 

 the doses prescribed have been too feeble. Judging by the results 

 of experiments on animals, one may say that the method which 

 consists in giving small daily doses of arsenious acid (the method 

 most frequently adopted in the treatment of human Trypano- 

 somiasis) is bad, and that it is preferable to administer large doses 

 at longer intervals. 



Writers are all agreed that human Trypanosomiasis is always 

 fatal as soon as the nervous symptoms declare themselves, but 

 before the appearance of these symptoms there is a period, more or 

 less long, during which the Trypanosomes, in small number in the 

 blood, produce but few morbid troubles. In this first phase it is 

 probable that the infection produced by Tr. gambiense is curable in 

 the human subject as it is in many species of animals, and that 

 arsenious acid may contribute to a cure. 



Good hygienic conditions and abundant food are also important 

 factors in the treatment of Trypanosomiasis ; in Africa the " sleeping 

 sickness " rages with a peculiar intensity among the miserable Negro 

 labourers, overworked and ill-fed. (Note — Christy, Eep. of the 

 Sleeping Sickness Comm., Nov. 1903: in Uganda the epidemic of 

 Trypanosomiasis has been greatly aggravated by famine.) The 

 same thing is observed among animals, those that have some defect 

 or some cause of enfeeblement are more strongly infected than 

 those which are in good condition and are supplied with abundant 

 food. — Comptes Rendxis, tome cxxxviii. p. 450 (22 Feb., 1904). 



Relations between the Development of the Tracheal Apparatus and 

 the Metamorphoses of Insects. By Jules Astglas. 



The phenomena of internal metamorphosis have in Insects a strict 

 relation to the development of the respiratory apparatus. 



The metamorphoses properly so-called, characterized by the phe- 

 nomena of histolysis followed by histogenesis, bear, moreover, even 

 among the Holometabolids, only on the middle portion of the 

 intestine, the muscles, and sometimes on the tracheal apparatus 

 itself. 



In the Hymenoptera that I have studied (Wasps, Bees) these 



