173 



by the discovery that an arsenate-free sample from a tank showed a 

 rapid decrease in arsenite and increase in arsenate on being left in an 

 open bottle for a few days, whereas fresh samples from a tank in which 

 no dipping had meanwhile taken place, showed no change in the same 

 time. Many bacteria, particularly those which infest the animal 

 intestine, have been detected in tank liquors and have been shown 

 to be capable of converting arsenate into arsenite, that is to say, the 

 ordinary fouhng of the liquor in the tank tends to maintain its efficiency 

 as a tick-kilhng dip. Unfortunately other organisms operating in the 

 opposite direction are apparently present. In those cases in w^hich the 

 tanks are frequently used, i.e., at least once a fortnight, practically 

 no arsenate may be present, but this is no proof that none is formed, 

 but rather that the arsenite-producing organisms overmaster the 

 action of those which operate in the other direction. These latter 

 appear to remain active in the tanks for a longer time than the former, 

 and consequently if the tanks remain out of use for a considerable 

 time the arsenate will be formed in increasing quantities. Dip liquor 

 from various tanks was exposed in the laboratory in narrow-necked 

 flasks, and also in shallow dishes and it was found that where the dips 

 were used once a week or only once a fortnight, the quantity of arsenate 

 formed within about a week in the flasks was either nil, or too little 

 to be detected with certainty, whilst oxidation was very rapid in the 

 open dishes, amounting in some cases to as much as half of the total 

 in 4 days. It is concluded that in tanks in use the conflicting actions 

 of the arsenate and arsenite formers result in the liquid being kept 

 sufficiently constant in composition for all practical purposes. Owners 

 of stock are therefore advised to continue using a dip unless there is 

 strong evidence that it has altered in composition. The article con- 

 cludes with a number of tables of results of analysis of tank hquor 

 under various conditions. 



Pringault (E.). Cimex pipistreUi, Jen., Agent de la Transmission de 

 la Trypanosomiase des Chauves-Souris. [Cimex pipistreUi, Jen., 

 the carrier of Trypanosomiasis in Bats.] — C.R. Soc. Biol., Paris, 

 Ixxvi, no. 19, 5th June 1914, pp. 881-884. 



The etiology of Trypanosoma vespertilionis, Batt., has hitherto been 

 unknown. Ecto-parasites and Culicidae have been suspected as 

 transmitters, but experiments made with Anopheles claviger and Culex 

 pipiens gave negative results. The ecto-parasites habitually found on 

 bats are bugs, fleas and Aroasidae. Gonder could discover nothing 

 in the fleas, the lice or the ticks, and believed that Leiognathus 

 arcttatus was the transmitting agent, but was unable to effect such 

 transmission because Leiognathus is incapable of hving more than 4 or 



5 days separated from bats, and the latter died in captivity after 



6 or 8 days. Nicolle and Comte considered the carrier to be either the 

 flea or the bug, because in a large number of bats examined, both 

 these parasites were invariably found on those which had trypanosomes 

 in their blood. In the present investigations 19 bats were taken from 

 one nest in which 118 parasites were found, 89 of them being bugs ; 

 examination of the crushed extract of some of these revealed the 

 presence of numerous trypanosomes. Bats, the blood of which showed 

 no trypanosomes after 8 days of constant examination, were regarded 



