vary
in different provinces, but the form of all _cash_ is the same."

"Very good. Thanks for letting me know at once. It seems to establish
a link with China, don't you think?"

"It does, but it merely adds to the mystery."

Coming out of the call-box, Stuart proceeded home, but made one or two
professional visits before he actually returned to the house. He now
remembered having left this particular _cash_ piece (which he usually
carried) in his dispensary, which satisfactorily accounted fro his
failure to find the coin in his waistcoat pocket. He had broken the
cork of a flask, and in the absence of another of correct size had
manufactured a temporary stopper with a small cork to the top of which
he had fixed the Chinese coin with a drawing-pin. His purpose served
he had left the extemporized stopper somewhere in the dispensary.

Stuart's dispensary was merely a curtained recess at one end of the
waiting-room and shortly after entering the house he had occasion to
visit it. Lying upon a shelf among flasks and bottles was the Chinese
coin with the cork still attached. He took it up in order to study
the inscription. Then:

"Have I cultivated somnambulism!" he muttered.

Fragments of black sealing-wax adhered to the coin!

Incredulous and half fearful he peered at it closely. He remembered
that the impression upon the wax sealing the mysterious envelope had
had a circular depression in the centre. It had been made by the head
of the drawing-pin!

He found himself at the shelf immediately above that upon which the
coin had lain. A stick of black sealing wax used for sealing medicine
was thrust in beside a bundle of long envelopes in which he was
accustomed to post his Infirmary reports!

One hand raised to his head, Stuart stood endeavouring to marshal his
ideas into some sane order. Then, knowing what he should find, he
raised the green baize curtain hanging from the lower shelf, which
concealed a sort of cupboard containing miscellaneous stores and not
a little rubbish, including a number of empty cardboard boxes.

A rectangular strip had been roughly cut from the lid of the topmost
box!

The mysterious envelope and its contents, the wax and the seal--all
had come from his own dispensary!

CHAPTER X

"CLOSE YOUR SHUTTERS AT NIGHT"

Inspector Dunbar stood in the little dispensary tapping his teeth with
the end of a fountain-pen.

"The last time he visited you, doctor--the time when he gave