175 



than 1 per mille. Further there is always some water at the bottom 

 of such boats, beneath the planking carrying the cargo. The experi- 

 ment showed that some of the fleas were not killed by the gas and that 

 rice weevils are even more resistant than fleas, so that they provide a 

 good control for experiments. The chances of escape for the fleas 

 increase with the size of the hold and the dampness of the cargo. 



Clayton gas however gives better results than any other substance 

 except hydrocyanic acid gas, which does not injure the goods, acts 

 more quickly, and is cheaper. Hydrocyanic acid gas may also be used 

 for cargoes that are not attractive to rats, such as machinery — in a 

 shipment of which fleas have been found. Experience has shown 

 that plague may be introduced in such cargoes. 



VAN Slooten (J.). Mededeeling omtrent eenige Proeven tot het 

 Ontratten van Goederenloodsen door Middel van Zwaveldioxyde 

 in zwakke Concentratie. [A Communication on some Tests 

 in freeing Goods-sheds from Rats by Fumigation with weak 

 Sulphur Dioxide.]— -Geneesk. Tijdschr. Ned.- Indie, Batavia, 

 Ixii, no. 3, 1921, pp. 340-345. 



During the outbreak of rat-plague at Tandjong-Priok in 1920, 

 an experiment was made to ascertain whether sulphur dioxide could 

 be used to drive rats into traps out of goods-sheds that did not admit 

 of regular fumigation as they could not be sufficiently sealed. It had 

 been noticed that animals try to avoid the fumes of SO, much too 

 weak to prove fatal. During some of the experiments from 0-054 

 to 0'21 volumes of SO2 per 1,000 of air were registered. Only some 

 of a number of marked rats were found in the traps, and the conclusion 

 reached is that SO,, used at a weak concentration, is not effective 

 in driving out rats under such circumstances. 



Leon (N.). A Case of Urethral Myiasis. — //. Parasitology, Urhana, 

 III., vii, no. 4, June 1921, pp. 184-185. 



A case of urethral myiasis from Rumania is recorded in which larvae 

 of Musca domestica were the causal agent. 



Campion (H.). Some Dragonflies and their Prey — ii. With Remarks 

 on the Identity oJ the Species of Orthetmvi involved. — Ann. & 

 Mai^. Nat. Hist., London, viii, no. 45, September 1921, pp. 240- 

 245*; 3 figs. 



Among the dragonflies recorded from Nyasaland, OrtJietntm brachiale, 

 P. de B., and 0. chrysostigma, Burm., are apparently the chief species 

 preying on Glossina morsitans, We.stw. 



WiLLiAiNis (C. B.). A Blood-sucking Thrips. — Entomologist, London, 

 liv, no. 698, July 1921, pp. 163-164. 



A Phloethripid, probably Trichothrips sp., is recorded as biting 

 man in Trinidad. In the subsequent number of this journal, p. 198, 

 Mr. E. E. Green describes similar experiences in Ceylon, and suggests 

 that the species concerned may be naturally a predatory one. It is 

 conceivable that in time a habitually blood-sucking race of thrips 

 may be evolved. 



