“Craig,” I remarked contemplatively, after a while, “how about Atherton himself?  Is he really free from the—­er—­stigmata, I suppose you call them, of insanity?”

“You mean, may the whole trouble lie with him?” he asked, not looking up from his work.

“Yes—­and the effect on her be a sort of reflex, say, perhaps the effect of having sold herself for money and position.  In other words, does she, did she, ever love him?  We don’t know that.  Might it not prey on her mind, until with the kind help of his precious relatives even Nature herself could not stand the strain—­ especially in the delicate condition in which she now finds herself?”

I must admit that I felt the utmost sympathy for the poor girl whom we had just seen such a pitiable wreck.

Kennedy closed his eyes tightly until they wrinkled at the corners.

“I think I have found out the immediate cause of her trouble,” he said simply, ignoring my suggestion.

“What is it?” I asked eagerly.

“I can’t imagine how they could have failed to guess it, except that they never would have suspected to look for anything resembling exophthalmic goiter in a person of her stamina,” he answered, pronouncing the word slowly.  “You have heard of the thyroid gland in the neck?”

“Yes?” I queried, for it was a mere name to me.

“It is a vascular organ lying under the chin with a sort of little isthmus joining the two parts on either side of the windpipe,” he explained.  “Well, when there is any deterioration of those glands through any cause, all sorts of complications may arise.  The thyroid is one of the so-called ductless glands, like the adrenals above the kidneys, the pineal gland and the pituitary body.  In normal activity they discharge into the blood substances which are carried to other organs and are now known to be absolutely essential.

“The substances which they secrete are called ’hormones’—­those chemical messengers, as it were, by which many of the processes of the body are regulated.  In fact, no field of experimental physiology is richer in interest than this.  It seems that few ordinary drugs approach in their effects on metabolism the hormones of the thyroid.  In excess they produce such diseases as exophthalmic goiter, and goiter is concerned with the enlargement of the glands and surrounding tissues beyond anything like natural size.  Then, too, a defect in the glands causes the disease known as myxedema in adults and cretinism in children.  Most of all, the gland seems to tell on the germ plasm of the body, especially in women.”

I listened in amazement, hardly knowing what to think.  Did his discovery portend something diabolical, or was it purely a defect in nature which Dr. Crafts of the Eugenics Bureau had overlooked?

“One thing at a time, Walter,” cautioned Kennedy, when I put the question to him, scarcely expecting an answer yet.