7 Topical Diseases due to Microscopic Organisms. 217 



explained by the fact that the same insect (louse) carries the two 

 infections. The commonest complications and sequalfe I have 

 observed were, in order of frequency, parotitis, often proceeding to 

 suppuration; gangrene of the feet ; polyarthritis; neuritis. Several 

 cases developed during convalescence symptoms of severe depres- 

 sion almost amounting to melancholia. 



As regards the prophylaxis of typhus, I am a believer in the 

 efficacy of taking every possible precaution against lice, especially 

 in the sterilization of all soldiers' underclothing and uniforms at 

 fixed intervals, and frequent bathing. As regards the use of 

 various substances which are deleterious to body-lice these are^ 

 according to the experiments carried out by Dr. Jackson and myself, 

 and in their order of efficiency: (1) petrol; (2) plain vaseline; 

 (3) guaiacol ; (4) anise preparations ; (5) iodoform ; (6) lysol, 

 cyllin, and similar preparations ; (7) carbolic acid solution (5 p.c.) ; 

 (8) naphthaline ; (9) camphor. We found that pyrethrum had a 

 very feeble action, while boric acid, sulphur, corrosive sublimate 

 and zinc sulphate, when used in powder form, had apparently 

 no action whatever. As regards bed-bugs, kerosene oil is the be.st 

 insecticide. Next to it comes guaiacol. It is interesting and most 

 important to note that an insecticide substance is not equally 

 efficacious against all parasites : a chemical having a very dele- 

 terious effect on lice may have practically no action on bed-bugs. 

 Iodoform, which kills lice in ten to fifteen minutes, has practi- 

 cally no action on bed-bugs, which may live for more than 

 twenty-fonr hours when exposed to it. It has also very little 

 effect on fleas. Pyrethrum, on the other hand, has a much more 

 powerful action on bed-bugs than on lice. It is useful, therefore, 

 in preparing insecticide powders for general use, to mix various 

 substances, some deleterious to lice, others to bed-bugs, and so on. 

 A very good combined powder is naphthaline and pyrethrum in 

 equal parts. 



For use against lice on a large scale, as among troops or 

 prisoners, perhaps the best insecticide powder is naphthaline. This 

 substance has a lower licecide action than kerosene oil, guaiacol, 

 iodoform, and anise preparations such as anethol, but it has a less 

 unpleasant odour than the first three named, and is much cheaper 

 than anethol powder. In stored blankets and clothing it is also 

 practicable and of use, as frequently lice are found upon the 

 clothing and blankets stored through the summer. Naphthaline 

 is useful for its well-known deterrent action upon moths. As 

 regards liquid insecticides, the American Sanitary Commission 

 sanctioned the use of kerosene by using it daily for troops and 

 prisoners. 



For the better class of patients, in practice a menthol powder 

 (menthol 8 to 5 gr., zinc. ox. 1 oz.) is to be preferred to naphtha- 

 line in most cases, as its odour is not unpleasant, while it is 



