ItEVIEW — TKOPICAL JIEDICINE, ETC. 225 



Masoni observed the presence of larval filaria in the blood of a camel in Egypt. Veterinary 

 Their presence in the peripheral blood was influenced to some extent by day and by night, Diseases— 

 as they were more easily found in smears taken late in the afternoon or at night. continued 



Mason also noted the presence of worms in the testicles and blood-vessels and excretory 

 tube of the epididymis of the camel. 



These worms resemble the Filaria papillosa, but are larger. Mason concluded that 

 these filaria in the testicles may be the mature forms of the microscopical larviE found in 

 the blood. 



Water. Simpson, ^ in an interesting paper, draws attention to the following points, 

 which may assist one in the search for water in an unknown locality. Water is more 

 easily obtained in a hilly than in a flat country, and can usually be found under waterless 

 rivers under the dry course of nullahs, at the junctions of ravines and valleys and at 

 the foot of hills. 



A well - wooded water - shed, and localities covered with vegetation and verdure, 

 invariably favour the presence of water. In the absence of vegetation, particular localities 

 over which fogs or swarming insects are noticed as a rule indicate water near the surface. 



In limestone districts and at the foot of hills springs are generally to be found, and 

 deep wells exist in localities abounding in sandstone. For drinking purposes, the ordinary 

 sources of water supply may be divided into (1) rainfall, (2) water derived from shallow 

 wells, (3) water derived from deep wells and springs, (4) surface waters, such as rivers, 

 lakes and tanks. 



Eainfall forms a very common source of supply in several parts of the Tropics. 



The rain is, as a rule, collected in storage tanks, which receive the rain from the 

 roof, or on large areas of ground which have been rendered more or less impermeable by 

 a covering of concrete, cement, or slate, and from this impermeable layer the rain-water 

 is led away into underground reservoirs by means of pipes. The method of collecting the 

 rainfall oS the roof is open to many objections in the Tropics owing to the chances of 

 contamination by dust, excreta of birds, and, it may be added, of insects {see " Diarrhcea," 

 page 38), and by dead organic vegetable matter. This may be avoided by various contrivances, 

 the objects of which are to reject the first washings off the roof and direct the remaining flow 

 into the tanks. The storage tanks should, as a nile, be made of slate, cement, or earthen- 

 ware, or simply consist of a tank built of bricks laid in cement. These storage tanks 

 should not be constructed of lead owing to the great absorbing properties of rain-water, 

 and, further, they should be placed upon the ground and covered with mosquito wire 

 netting. It is an advantage to have them covered in, so as to prevent the ingress of 

 insects, rats and dust. They ought at periodic intervals to be cleaned out, and it is essential 

 that the overflow-pipe should communicate with the open air. A further improvement 

 could be made by adding a sand filter which would receive the rain direct from the 

 roof before reaching the vats. 



Eeference may be made to a very common source of water supply in the Tropics, viz., 

 wells. As a rule, three types of wells are met with — shallow, deep, and artesian wells — and 

 a reference to the use and abuse of these wells in the Tropics might well be made here. 

 Shallow wells may vary in depth from two to fifty feet, and they derive their water supply 

 from the sub-soil water. The chief objection to shallow wells is the readiness with which 

 they become polluted from cesspools and surface drainage, which form the commonest 

 sources of contamination in the Tropics. 



In some parts it is not an uncommon sight to see natives performing the act 

 of ablution at the mouth of a surface weU, and it does not require much imagination to 

 see how such a well becomes contaminated. Further, the proximity of the well to burial- 

 grounds, cesspools and other filth accumulations, does not improve its chances of escaping 

 contamination. It is essential, if surface-wells are to be used, that the ground should be 

 quite clear for a radius of at least 100 feet, and the ground water level should be not less 

 than twelve feet from the surface. 



William Dawson,^ in an interesting paper on the supply of drinking-water in India and 

 its connection with sub-soil water, suggests that much might be done to further improve the 



> Mason, E. (1906), "Filaria in the Blood of Camels in Egypt." Journal of Comparative Faiholog]i and 

 Therapeutics, p. 118. 



- Simpson, W. J., etc. (May Ist, 1903), "Water Supplies." Journal of Tropical Medicine, p. 132. 



" Dawson, A. W. (January 1st, 1907), " The Supply of Drinking Water in India, and its Connection with 

 the Sub-Soil Water." Journal of the Royal Institute of Public Health, p. 33, Vol. XV., No. 1. 



