93 



found that flies were breeding in large numbers in the latrine trenches 

 just outside the jail, in spite of the fact that the trenching was carried 

 out most carefully and that a covering of five inches of earth was used. 

 FUes began to appear about ten days after the trench was filled, reached 

 their maximum in about a month and then continued appearing for 

 about a fortnight. It was found that the mature larva makes its 

 way into the earth covering the excreta and pupates when it arrives 

 just below the surface. The earth covering therefore actually assists 

 the issue of flies and the more carefully the trenching is carried out, 

 the more securely are the larvae protected against their natural 

 enemies. The crows and kites which feed on the larvae in badly- 

 managed trenching grounds, were not present. This discovery pointed 

 to the desirability of destroying the eggs or larvae in the excrement 

 prior to covering it. Of three contiguous pits, one was covered in the 

 ordinary way, in the second a pint of borax solution (1 dram to a pint 

 of water) was poured over the excreta and in the third a quarter of a 

 pint of crude petroleum was sprinkled. All the pits were covered with 

 earth ; gauze frames placed over them showed that 446 flies emerged 

 from the first, 61 from the second, and 246 from the third. The 

 experiment was repeated on a fresh series of three pits with stronger 

 solutions of borax and with the same amount of crude petroleum, no 

 control pit being used. From the petroleum pit 34 flies issued, from 

 the pit with borax, half an ounce to the pint, 77 flies issued, and from 

 the third pit with borax, one ounce to the pint, 74 flies issued. The 

 experiments were not completed as the author was transferred. The 

 monthly cost of petroleum locally would be about 3s. 4d. for the total 

 jail population of about 450 and with double this amount it seems likely 

 that the breeding could be completely stopped. That the flies were 

 probably responsible for the dysentery is shown by the fact that in 

 1915 there were only five cases among the convicts compared with 

 an average of 27*6 for the previous five years. No case of enteric 

 occurred in 1915. 



S'ERGENT (Edm.) & Sergent (Et.). Alternance des 6coulements d'eau, 

 principe directeur des mesures antilarvaires. [The alternation of 

 water out-flows as the leading principle of antilarval measures.] — 

 La Malariologia, Naples, (Ser I, ix, no. 1) Ser. II, i, no. 1, 29th 

 February 1916, pp. 3-9, 4 figs. 



At the beginning of their anti-malarial campaigns in Algeria in 

 1902 the authors established anti-mosquito brigades, which required 

 continual supervision, much work and considerable expense. Experience 

 has suggested a new method which is extremely simple, always efficient, 

 and very cheap, as one or two workmen require but a few minutes each 

 week to carry it out. This new method is often the only anti-larval 

 measure necessary and is based on the fact that in the Algerian Tell 

 region, i.e., the region suitable for colonisation, Anopheline larvae live 

 on an average for three weeks. Thus the formation of a breeding place 

 may be tolerated without any danger ensuing, provided it is auto- 

 matically dried up in less than three weeks, thus destroying the 

 larvae. To obtain this result it is sufficient to prevent the water from 

 remaining more than one week in one and the same spot. In practice 

 this is attained by alternating the out-flow of the water each week. 

 Two drain-channels, instead of one, must be made for each spring, and 



