"What is the matter with him, doctor?" asked Mrs. Selby.

"It is, I think, a case of what is called blood-clot, which has formed
in the veins of the leg," I answered. "Part of this clot has been
detached by exertion, or possibly by rubbing, and, travelling upwards,
has become impacted in one of the pulmonary arteries."

"Is it serious?" asked the poor wife.

"Of course we must hope for the best," I said; "but it is my duty to
tell you that I do not myself think Major Selby will recover; how long
he will last depends upon the size of the clot which has got into the
artery."

"Oh, this is ridiculous," broke in Mr. Selby. "My brother has been under
the care of Sir John Bell, the ablest doctor in Dunchester, who told him
several times that he was suffering from nothing but rheumatism, and
now this gentleman starts a totally different theory, which, if it
were true, would prove Sir John to be a most careless and incompetent
person."

"I am very sorry," I answered; "I can only hope that Sir John is right
and I am wrong. So that there may be no subsequent doubt as to what I
have said, with your leave I will write down my diagnosis and give it to
you."

When this was done I returned to the patient, and Mr. Selby, taking
my diagnosis, telegraphed the substance of it to Sir John Bell for his
opinion. In due course the answer arrived from Sir John, regretting that
there was no train by which he could reach Dunchester that night,