When a battalion medical officer or sanitary officer wishes to make a report or suggestion he does so through the A.D.M.S. of the division. In the same way the A.D.M.S. of the division communicates with the D.D.M.S. of the corps; the D.D.M.S. of the corps with the D.M.S. of the army, and the D.M.S. of the army with the D.G.M.S. at G.H.Q. A battalion medical officer cannot go over the head of his A.D.M.S., nor could the latter pass his D.D.M.S. to make a report or suggestion. Everything must go up or down the system through the various heads, and no side stepping is permitted. The front line trenches were about seven miles from our laboratory which was located in a town with three casualty clearing stations, a railroad and canal. This made it possible to evacuate the wounded rapidly to the base by means of hospital trains and barges during an engagement. The system which enables a sick or wounded man to be removed from the front is simple enough. Each day the medical officer of a battalion, who himself may be located in a dug-out in the trenches themselves or in a cellar of a house not far behind the trenches, holds a "sick parade" at his "regimental aid post." During a battle the wounded are collected by the regimental stretcher bearers and brought to the aid post. Any soldier who is feeling unwell reports to the M.O. of the battalion who, if the trouble is a minor one, may give him some suitable medicine. It is one of the difficulties of the M.O. to distinguish between a case of genuine illness and a fakir or "scrimshanker," and a good supply of common sense and a knowledge of human nature is a great asset in making correct diagnoses. It is almost impossible, for example, to distinguish between a genuine case of rheumatism and a clever imitation of it, because the only symptoms are pains, the effects of which can easily be simulated by a soldier. If the man shows serious symptoms he is sent back to the "advanced dressing station" which will probably be a mile or so behind the front line trenches, if possible in a house and on a road accessible to motor ambulances. If the man can walk he goes through the nearest communication trench; if wounded he is given first aid, and if unable to walk he is helped or carried back by stretcher bearers from the ambulance--to the dressing station.