The great danger which may arise from an exceedingly minute portion of septic matter renders great caution necessary on the part of those who might, by a little indiscretion, convey it from one to another. Thus a number of years ago a medical man was nearly driven mad by an epidemic of puerperal fever which he had in his practice : one patient dying after the other. In order to get rid of any infection, he burnt all his clothes and went away for three months. During his absence everything went well. On his return the epidemic again broke out: on careful investigation he found the only thing he had forgotten to burn was his gloves, and these had acted as a reservoir of infection. The hands, imperfectly cleansed in the first instance, had conveyed the septic matter into the gloves, and there it remained, re-infecting the hands every time the gloves were put on. In the same way a thermometer may prove a cause of continual infection unless the thermometer be carefully washed, and, if necessary, disinfected, each time it is used and before it is put into the case. In a similar manner it has been found that gonorrhoeal matter may remain in the vagina and infect several persons without the woman herself ever suffering. One of the best antiseptics for disinfection in such cases is permanganate of potassium. This may be used to wash out abscesses, if there is any fear of danger from absorption of carbolic acid; and also as a lotion for ulcers or wounds about the mouth, the urethra, or anus, where the carbolic acid might be too irritating; as is evident from Koch's experiment, however (vide p. 92), a solution of the strength ordinarily used - one per cent., i.e. four grains to the ounce - is not sufficient to destroy the septic organism, although one of five times the strength will do so.

Another way in which septic poisoning may be produced is by the introduction of a catheter into the bladder, where this cannot be completely emptied naturally on account either of paralysis, enlarged prostate, or stricture. So long as the contents of the bladder have not come in contact with any foreign matter they may remain in the bladder for some time without undergoing decomposition, but if a dirty catheter should be passed, and thus a few organisms introduced into the bladder, decomposition may set up in the urine and septic poisoning ensue. A solution of carbolic acid in oil is sometimes trusted to for the disinfection of catheters, but, as Koch's experiments (p. 96) show that such a solution has little or no antiseptic power, the catheters should be disinfected by a strong solution of carbolic acid in water, and afterwards oiled before their introduction.