Please let me know the result of your examination of this rat. (Signed) D.M.S. Z Army. 3. _D.M.S. Z Army._ I have not received this rat. (Signed) O.C. No. 1 Mobile Lab'y. 4. _To D.D.M.S. J. Corps._ With reference to attached, will you please say what has become of this rat. (Signed) D.M.S. Z Army. 5. _To D.M.S. Z Army._ It has been sent to Canadian laboratory and report has been called for. (Signed) D.D.M.S. J. Corps. 6. _To O.C. (Canadian) Mobile Laboratory._ Will you please let me know the result of your examination of this rat. (Signed) D.M.S. Z Army. 7. _To D.M.S. Z Army._ This rat was quite normal and had evidently been killed by a blow. The report was forwarded to A.D.M.S. K. Div. (Signed) O.C. No. 5 (Can.) Mobile Lab. Even a partly decomposed rat was unable to escape the army system. CHAPTER XI LABORATORY WORK IN THE FIELD. With the medical organization of the army in mind it may be seen that a small mobile laboratory might be of great practical service to the army in the field. Under the conditions which exist in the present war, the army itself is not very mobile, nor is it necessary for the laboratory to be, but it is of great importance to have a car which will permit of the area being covered quickly should a specimen, sample or investigation be required. The car is the really essential mobile part of the unit. Our laboratory had charge of both the bacteriological and hygiene work of a given area; it was the only laboratory that did both types of work. When our apparatus had been unpacked and set up in the old ball room of the Hotel de Ville it made quite an imposing show, and after we saw what equipment the other laboratories had we were decidedly proud of ours. Our first bit of work proved to be the examination of a number of soldiers who had been in contact with a case of cerebro-spinal meningitis, to detect "carriers" of the specific germ. Then material of all sorts began to come in for examination from the casualty clearing stations, field ambulances, sanitary and medical officers, rest stations and other places. Most of the routine bacteriological work proved to be of much the same nature as that done in a health laboratory at home, and consisted of examinations to detect some of the ordinary communicable diseases such as diphtheria, cerebro-spinal meningitis, typhoid fever, malaria, dysentery, tuberculosis, and venereal diseases. Should a case of diphtheria, for example, be found in a soldier, all his immediate friends and companions with whom he had been in contact, would be swabbed to see whether they were infected. Those found to be infected would be removed from the army at once.