“Why—­yes,” answered Elaine, following Craig with her deep eyes.  “Poor Rusty.  He woke me up this morning.  He feels as badly as I do, poor old fellow.”

Craig reached down and gently pulled the collie out into the room.  Rusty crouched down close to the floor.  His nose was hot and dry and feverish.  He was plainly ill.

“How long has Rusty been in the room?” asked Craig.

“All night,” answered Elaine.  “I wouldn’t think of being without him now.”

Kennedy lifted the dog by his front paws.  Rusty submitted patiently, but without any spirit.

“May I take Rusty along with me?” he asked finally.

Elaine hesitated.  “Surely,” she said at length, “only, be gentle with him.”

Craig looked at her as though it would be impossible to be otherwise with anything belonging to Elaine.

“Of course,” he said simply.  “I thought that I might be able to discover the trouble from studying him.”

We stayed only a few minutes longer, for Kennedy seemed to realize the necessity of doing something immediately and even Dr. Hayward was fighting in the dark.  As for me, I gave it up, too.  I could find no answer to the mystery of what was the peculiar malady of Elaine.

Back in the laboratory, Kennedy set to work immediately, brushing everything else aside.  He began by drawing off a little of Rusty’s blood in a tube, very carefully.

“Here, Walter,” he said pointing to the little incision he had made.  “Will you take care of him?”

I bound up the wounded leg and gave the poor beast a drink of water.  Rusty looked at me gratefully from his big sad brown eyes.  He seemed to appreciate our gentleness and to realize that we were trying to help him.

In the meantime, Craig had taken a flask with a rubber stopper.  Through one hole in it was fitted a long funnel; through another ran a glass tube.  The tube connected with a large U-shaped drying tube filled with calcium chloride, which, in turn, connected with a long open tube with an upturned end.

Into the flask, Craig dropped some pure granulated zinc.  Then he covered it with dilute sulphuric acid, poured in through the funnel tube.

“That forms hydrogen gas,” he explained to me, “which passes through the drying tube and the ignition tube.  Wait a moment until all the air is expelled from the tubes.”

He lighted a match and touched it to the open, upturned end.  The hydrogen, now escaping freely, was ignited with a pale blue flame.

A few moments later, having extracted something like a serum from the blood he had drawn off from Rusty.  He added the extract to the mixture in the flask, pouring it in, also through the funnel tube.

Almost immediately the pale, bluish flame turned to bluish white, and white fumes were formed.  In the ignition tube a sort of metallic deposit appeared.

Quickly Craig made one test after another.