The common sense and resourcefulness of the British sanitary officer is well shown by this solution of a difficult and apparently hopeless problem. It is indeed a difficult problem which a British officer will acknowledge to be hopeless, and it is this very British quality that the Hun should always keep in mind in thinking of the end of the war and the reckoning afterwards. As far as we know there has been no plague among the warring armies in Europe. Plague is conveyed from rats having this disease to human beings by means of rat fleas. These fleas become infected by biting the infected rats and subsequently infect human beings by biting them. There are plenty of rats in the trenches and dugouts, particularly in winter; in the summer they breed along the water courses, and in the autumn are attracted to the trenches where there is plenty of waste food to be had. Numerous devices are used to destroy them, and it is a common thing to see a soldier sitting patiently in the trenches with his rifle between his knees and a piece of toasted cheese on the end of his bayonet. As Mr. Rat, attracted by the savoury odour, approaches and takes the first sniff, the trigger is pulled and there is one living rat less. Prizes are sometimes given to the man who can kill the largest number in a week, and bags of 25 and 30 are not uncommon. Sometimes poison is used, and even ferrets have been employed with, however, little success. In connection with the rat problem, we had an illustration of how impossible it is even for a rat to escape the British army system. Army routine, the result of many years of experience, once put into operation is as sure and certain as death and taxation. The regulations are that if any considerable number of rats have been noticed around the trenches sick or dying, some of them shall be sent to the field laboratories for examination. Bubonic plague is a rat disease; consequently if rats are dying in any great numbers, we would conclude that some disease, possibly plague, must be the cause. In this case the Director of Medical Services of the army had been notified that a rat had been despatched to a laboratory for examination. Consequently he was anxious to know the result of the examination, and when a report was not forthcoming he sent a telegram to the officer commanding the Canadian laboratory asking that a report on the rat be forwarded at once. As we had not received the rat we reported the same to the D.M.S. who put the matter up to the D.D.M.S. of the corps who had forwarded the rat. The rat had gone to another laboratory, and "the system" to locate the rat was put into operation. The following is the correspondence upon the subject: 1. _To D.D.M.S. J. Corps._ In accordance with your 1w/ER, 16 of 1/2/3, a rat is being sent from trench x.y.z. to No. 1 mobile laboratory at ----. (Signed) A.D.M.S. K. Div. 2. _To O.C. No. 1 Mobile Laboratory._