Some things I knew already.  Barnes was comparatively wealthy, and had evidently the stamp of approval of Maude Euston’s father.  As for Lane, he was far from wealthy, although ambitious.

The company was in a delicate situation where an act of omission would count for as much as an act of commission.  Whoever could foresee what was going to happen might capitalize that information for much money.  If there was a plot and Barnes had been a victim, what was its nature?  I recalled Miss Euston’s overheard conversation in the tea-room.  Both names had been mentioned.  In short, I soon found myself wondering whether some one might not have tempted Lane either to do or not to do something.

“I wish you’d go over to the St. Germaine, Walter,” remarked Kennedy, at length, looking up from his work.  “Don’t tell Miss Euston of Lane’s visit.  But ask her if she will keep an eye out for that woman she heard talking—­and the man, too.  They may drop in again.  And tell her that if she hears anything else, no matter how trivial, about Barnes, she must let me know.”

I was glad of the commission.  Not only had I been unable to arrive anywhere in my conjectures, but it was something even to have a chance to talk with a girl like Maude Euston.

Fortunately I found her at home and, though she was rather disappointed that I had nothing to report, she received me graciously, and we spent the rest of the evening watching the varied life of the fashionable hostelry in the hope of chancing on the holders of the strange conversation in the tea-room.

Once in a while an idea would occur to her of some one who was in a position to keep her informed if anything further happened to Barnes, and she would despatch a messenger with a little note.  Finally, as it grew late and the adventuress of the tea-room episode seemed unlikely to favor the St. Germaine with her presence again that night, I made my excuses, having had the satisfaction only of having delivered Kennedy’s message, without accomplishing anything more.  In fact, I was still unable to determine whether there was any sentiment stronger than sympathy that prompted her to come to Kennedy about Barnes.  As for Lane, his name was scarcely mentioned except when it was necessary.

It was early the next morning that I rejoined Craig at the laboratory.  I found him studying the solution which he had extracted from the blood-soaked gauze after first removing the blood in a little distilled water.

Before him was his new spectroscope, and I could see that now he was satisfied with what the uncannily delicate light-detective had told him.  He pricked his finger and let a drop of blood fall into a little fresh distilled water, some of which he placed in the spectroscope.

“Look through it,” he said.  “Blood diluted with water shows the well-known dark bands between D and E, known as the oxyhemoglobin absorption.”  I looked as he indicated and saw the dark bands.  “Now,” he went on, “I add some of this other liquid.”