As Mrs. Blake stretched out her slender hand, drawn with pain, to his silky head, he gave a little yelp of delight and his little red tongue eagerly caressed her hand.

It was as though the two understood each other.  Although Mrs. Blake, as yet, had no more idea what had happened to her pet, she seemed to feel by some subtle means of thought transference that the intelligent little animal was conveying to her a message of hope.  The caress, the sharp, joyous yelp, and the happy wagging of the bushy tail seemed to brighten her up, at least for the moment, almost as if she had received a new impetus.

“Buster!” she exclaimed, overjoyed to get her pet back again in so much improved condition.

“I wouldn’t exert myself too much, Mrs. Blake,” cautioned Kennedy.

“Were—­were there any germs in the letter?” she asked, as Reginald and Betty stood on the other side of the chair, much encouraged, apparently, at this show of throwing off the lethargy that had seized her.

“Yes, but about as harmless as those would be on a piece of cheese,” Kennedy hastened.  “But I—­I feel so weak, so played out—­ and my head—­”

Her voice trailed off, a too evident reminder that her improvement had been only momentary and prompted by the excitement of our arrival.

Betty bent down solicitously and made her more comfortable as only one woman can make another.  Kennedy, meanwhile, had been talking to Miss Rogers, and I could see that he was secretly taking her measure.

“Has Dr. Wilson been here this morning?” I heard him ask.

“Not yet,” she replied.  “But we expect her soon.”

“Professor Kennedy?” announced a servant.

“Yes?” answered Craig.

“There is someone on the telephone who wants to speak to you.  He said he had called the laboratory first and that they told him to call you here.”

Kennedy hurried after the servant, while Betty and Reginald joined me, waiting, for we seemed to feel that something was about to happen.

“One of the unofficial detectives has unearthed a clue,” he whispered to me a few moments later when he returned.  “It was Garwood.”  Then to the others he added, “A car, repainted, and with the number changed, but otherwise answering the description of Dr. Wilson’s has been traced to the West Side.  It is somewhere in the neighborhood of a saloon and garage where drivers of taxicabs hang out.  Reginald, I wish you would come along with us.”

To Betty’s unspoken question Craig hastened to add, “I don’t think there is any immediate danger.  If there is any change—­let me know.  I shall call up soon.  And meanwhile,” he lowered his voice to impress the instruction on her, “don’t leave your mother for a moment—­not for a moment,” he emphasized.

Reginald was ready and together we three set off to meet Garwood at a subway station near the point where the car had been reported.  We had scarcely closed the front door, when we ran into Duncan Baldwin, coming down the street, evidently bent on inquiring how Mrs. Blake and Betty were.