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under trial. This was effected by enclosing them in wire-gauze frames 

 covered Avith thin muslin and suspending these next to the skin in 

 various positions on the body. Trials were made with the alkaloid 

 cytisine derived from the seeds of gorse and laburnum and possessing 

 similar physiological properties to those of nicotine, but being much 

 less volatile. Preliminary trials with naphthaline showed that the 

 diffusion of vapour over the body surface under the clothing is restricted 

 to a very small area round the centre of distribution. Thus naph- 

 thaline WTapped in motor veiling and put into a bag containing lice 

 killed them in three hours but in another bag only half an inch from the 

 first, only two larvae and one adult were dead out of 30 after 1 1 hours. 

 By arranging a series of five cages, containing lint saturated with the 

 remedy to be tested, and only containing lice in every alternate one, 

 the effect of contact and diffusion were observed at the same time. 

 Naphthaline, sulphur, cresylic acid, iodoform, vaseline with naph- 

 thaline, kerosine oil and benzole, vermijelli with cresylic acid, cytisine, 

 vermijelli with phenol, were all tried. The general result, except in the 

 case of vermijelli alone, was that of the lice in contact with the lint all 

 or nearly all died. The result of these trials is to suggest that the 

 effect by diffusion of all these substances, except possibly of naph- 

 thaline, is so slight as to reduce them all to the level of contact remedies. 

 Thorough impregnation of the clothing would therefore be necessary 

 to produce any effect. Naphthaline in powder is likely to be wasted, 

 and if made into tablets, evaporates too slowly to produce any real 

 effect, while even if clothing be impregnated with it, its efficacy is lost 

 on the second day. Experiments on the value of soaking shirting in 

 the remedy were made as follows : — Shallow cardboard boxes 1 inch 

 in diameter and f inch deep were lined vnth. flannel shirting which had 

 been washed and dried by the ordinary laundry process and then soaked 

 in a solution of the remedy and dried off rapidly ; the open side of the 

 boxes was covered with chiffon through which the insects fed. These 

 boxes were kept by day in a linen bag suspended beneath the clothing 

 and at night beneath a belt with the chiffon side next the skin, the 

 available feeding period being about seven hours. The remedies 

 tested were sulphur, vermijelli, vermijelli and cresyhc acid, vermijelli 

 and naphthaline. The results were almost nil except with vermijelli 

 and naphthaline ; in all other cases, eggs were laid on the flannel as 

 in the control. A second test made with flannel impregnated two days 

 previously, showed that the vermijelli-naphthaline preparation rapidly 

 loses its effectiveness by evaporation. Trials were then made with 

 lice on pieces of flannel soaked in six different solutions and enclosed 

 in pockets of fine chiffon, worn next to the skin. An emulsion of 

 carbolic acid and soft soap was the most effective of these, the practical 

 effect of the impregnation lasting six or seven days while the odour 

 might act as a deterrent for a few days longer. Cytisine appears to be 

 effective experimentally, but its toxic effect might be serious if it is used 

 to impregnate garments ; it is also very costly. These trials suggest 

 that a practical remedy for preventing the spread of lice among troops 

 may be an emulsion consisting of 45-50 per cent, of soft soap combined 

 by heating with 50-55 per cent, crude carbolic acid. Garments should 

 be impregnated with a 5 per cent, solution of this emulsion in warm 

 water and thoroughly dried before use. The cost, apart from labour, 

 is about Id. per shirt. 



