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isolated by Chagas. The aiitlior was able to obtain a supply of 

 this virus and 19 mice seriously infected in tlie early days of 

 their life in May 1912 were inoculated, some on the 5tli December 

 and others on the 20th of the same month, with large doses of the 

 Chagas virus at the same time with 30 controls of the same age 

 and the same brood. The result was relatively clear. All the 

 controls died between 15th and 25th day and of the 19 mice 

 cured of their Bahia infection, nine are still alive, although after 

 11 and 13 weeks a few trypanosomes were still to he found in 

 their blood. The ten dead mice exhibited a lengthy incubation 

 of two to four weeks. These experiments proved that the first 

 attack with the Bahia virus confers a considerable resistance to 

 considerable doses of the Chagas virus. The author remarks that 

 this latter virus appears to have acquired a very great virulence 

 for mice. He experimented with two fresh larvae of C'j/iorrJtinus 

 without result, and obtained no flagellate forms from their 

 excreta. Experiments were further made with hundreds of bugs, 

 Cijnex lectularius and C. rotundatus. Both species are infected 

 to a considerable degree, 80 per cent, on the average, and their 

 dejecta contained metacyclic trypanosomes. The poison obtained 

 was injected into young- mice three or four days old whose 

 brothers and sisters served as controls. Results were very 

 curious, the mice were very slightly infected and both they and 

 the controls recovered from the infection in a few days. The 

 metacyclic form of T. cruzi has a considerable power of penetra- 

 tion. The dejecta of ConorrJiimis placed in the mouth or in the 

 rectum of mice or on the nipple, that is to say in places where 

 there were no excoriations, produced certain infections. By 

 placing the dejecta on the skin of four mice, aged two days, then 

 suspending them bj' thread for three hours in a moist atmosphere 

 and carefully washing them at the end of the experiments, the 

 author succeeded in infecting all. This experiment shows that it 

 is at least possible with trypanosomes to produce infection 

 through the skin, and it is probable that man is infected in this 

 way through the mucous membrane of the mouth, because Cono- 

 rrhimis generally bites the face and lips of sleeping individuals. 

 After feeding, and sometimes before, the dejecta of these insects 

 are abundant and may readily come into contact with the buccal 

 mucous membrane. The author draws special attention to the 

 fact elucidated by his experiments, that the virus loses a large 

 part of its intensity in passing through an intermediate host. 

 Oonder has shown that a race of T. lewisi capable of resisting 

 arsenophenylglycine, loses its resistance after passage through 

 the rat louse, Haematopinus spimilosus, about the 10th day, 

 and it would appear that passage through an invertebrate host 

 causes it to lose ^11 the physiological characters which laboratory 

 exj)eriments have given it; hence a certain number of these lose 

 their value, and it is necessary that all experiments should be 

 performed with natural virus. The author further remarks that 

 the fact that certain animals are artificially sensible to a virus, 

 does not prove that they can be infected in nature through the 

 intervention of an intermediate host, and gives two typical 

 examples. Red frogs which are very sensible to injections of 

 Trypanosoma inopinatinn may be bitten by hundreds of infected 

 leeches for several months without receiving infection, whilst 



