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._

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 org