“And you have discovered in this case?” I asked.

“That the blood on the bandage from the face of that woman who escaped was not the blood of a pure Caucasian.  She shows traces of negro blood, in fact exactly what would have been expected of a mulatto.”

It dawned on me that the woman must have been Marie, after all; at least that that was what he meant.

“But,” I objected, “one look at her face was enough to show that she was not the dark-skinned Marie with her straight nose, her dark hair and other features.  This woman was fair, had a nose that was almost hooked and hair that was almost flaxen.  Remember the portrait parle.”

“Just so—­the portrait parle.  That is what I am remembering.  You recall Carton discovered that in some way these people found out that we were using it?  What would they do?  Why, they have thought out the only possible way in which to beat it, don’t you see?

“Marie, Madame Margot, whatever you call her, had a beauty parlour.  Oh, they are clever, these people.  They reasoned it all out.  What was a beauty parlour, a cosmetic surgery, for, if it could not be used to save them?  They knew we had her scientific description.  What was the thing to do, then?  Why, change it, of course, change her!”

Kennedy was quite excited now.

“You know what Miss Kendall said of decorative surgery, there?  They change noses, ears, foreheads, chins, even eyes.  They put the thing up to Dr. Harris with his knives and bandages and lotions.  He must work quickly.  It would take all his time.  So he disappeared into Margot’s and stayed there.  Marie also stayed there until such time as she might be able to walk out, another person entirely.  Harris must have had charge of her features.  The attendants in Margot’s had charge of her complexion and hair—­ those were the things in which they specialized.

“Don’t you see it all now?  She could retire a few days into the dope joint next door and she would emerge literally a new woman ready to face us, even with Bertillon’s portrait parle against her.”

It was amazing how quickly Kennedy pieced the facts together into an explanation.

“Yes,” he concluded triumphantly, “that blonde woman was our dark-skinned mulatto made over—­Marie.  But they can’t escape the power of science, even by using science themselves.  She might change her identity to our eyes, but she could not before the Reichert test and the microscope.  No, the Ethiopian could not change her skin before the eye of science.”

It was late in the afternoon that Kennedy received a hurried telephone call from Miss Kendall.  I could tell by the scraps of conversation which I overheard that it was most important.

“That girl, Sybil Seymour, has broken down,” was all he said as he turned from the instrument.  “She will he here to-day with Miss Kendall.  You must see Carton immediately.  Tell him not to fail to be here, at the laboratory, this afternoon at three, sharp.”