"You were late this morning, John," she remarked, after a pause.

"Yes, Ada; I slept badly. Some little cerebral congestion, no doubt due to over-stimulation of the centres of thought. I have been a little disturbed in my mind."

His sister stared across at him in astonishment. The Professor's mental processes had hitherto been as regular as his habits. Twelve years'

continual intercourse had taught her that he lived in a serene and rarefied atmosphere of scientific calm, high above the petty emotions which affect humbler minds.

"You are surprised, Ada," he remarked. "Well, I cannot wonder at it. I should have been surprised myself if I had been told that I was so sensitive to vascular influences. For, after all, all disturbances are vascular if you probe them deep enough. I am thinking of getting married."

"Not Mrs. O'James?" cried Ada Grey, laying down her egg-spoon.

"My dear, you have the feminine quality of receptivity very remarkably developed. Mrs. O'James is the lady in question."

"But you know so little of her. The Esdailes themselves know so little.

She is really only an acquaintance, although she is staying at The Lindens. Would it not be wise to speak to Mrs. Esdaile first, John?"

"I do not think, Ada, that Mrs. Esdaile is at all likely to say anything which would materially affect my course of action. I have given the matter due consideration. The scientific mind is slow at arriving at conclusions, but having once formed them, it is not p.r.o.ne to change.

Matrimony is the natural condition of the human race. I have, as you know, been so engaged in academical and other work, that I have had no time to devote to merely personal questions. It is different now, and I see no valid reason why I should forego this opportunity of seeking a suitable helpmate."

"And you are engaged?"

"Hardly that, Ada. I ventured yesterday to indicate to the lady that I was prepared to submit to the common lot of humanity. I shall wait upon her after my morning lecture, and learn how far my proposals meet with her acquiescence. But you frown, Ada!"

His sister started, and made an effort to conceal her expression of annoyance. She even stammered out some few words of congratulation, but a vacant look had come into her brother's eyes, and he was evidently not listening to her.

"I am sure, John," she said, "that I wish you the happiness which you deserve. If I hesitated at all, it is because I know how much is at stake, and because the thing is so sudden, so unexpected." Her thin white hand stole up to the black cross upon her bosom. "These are moments when we need guidance, John. If I could persuade you to turn to spiritual----"

The Professor waved the suggestion away with a deprecating hand.

"It is useless to reopen that question," he said. "We cannot argue upon it. You a.s.sume more than I can grant. I am forced to dispute your premises. We have no common basis."

His sister sighed.

"You have no faith," she said.

"I have faith in those great evolutionary forces which are leading the human race to some unknown but elevated goal."

"You believe in nothing."

"On the contrary, my dear Ada, I believe in the differentiation of protoplasm."

She shook her head sadly. It was the one subject upon which she ventured to dispute her brother's infallibility.

"This is rather beside the question," remarked the Professor, folding up his napkin. "If I am not mistaken, there is some possibility of another matrimonial event occurring in the family. Eh, Ada? What!"

His small eyes glittered with sly facetiousness as he shot a twinkle at his sister. She sat very stiff, and traced patterns upon the cloth with the sugar-tongs.

"Dr. James M'Murdo O'Brien----" said the Professor sonorously.

"Don't, John, don't!" cried Miss Ainslie Grey.

"Dr. James M'Murdo O'Brien," continued her brother inexorably, "is a man who has already made his mark upon the science of the day. He is my first and my most distinguished pupil. I a.s.sure you, Ada, that his 'Remarks upon the Bile-Pigments, with special reference to Urobilin,' is likely to live as a cla.s.sic. It is not too much to say that he has revolutionised our views about Urobilin."

He paused, but his sister sat silent, with bent head and flushed cheeks.

The little ebony cross rose and fell with her hurried breathings.

"Dr. James M'Murdo O'Brien has, as you know, the offer of the physiological chair at Melbourne. He has been in Australia five years, and has a brilliant future before him. To-day he leaves us for Edinburgh, and in two months' time he goes out to take over his new duties. You know his feeling towards you. It rests with you as to whether he goes out alone. Speaking for myself, I cannot imagine any higher mission for a woman of culture than to go through life in the company of a man who is capable of such a research as that which Dr.

James M'Murdo O'Brien has brought to a successful conclusion."

"He has not spoken to me," murmured the lady.

"Ah, there are signs which are more subtle than speech," said her brother, wagging his head. "You are pale. Your vasomotor system is excited. Your arterioles have contracted. Let me entreat you to compose yourself. I think I hear the carriage. I fancy that you may have a visitor this morning, Ada. You will excuse me now."

With a quick glance at the clock he strode off into the hall, and within a few minutes he was rattling in his quiet, well-appointed brougham through the brick-lined streets of Birchespool.

His lecture over, Professor Ainslie Grey paid a visit to his laboratory, where he adjusted several scientific instruments, made a note as to the progress of three separate infusions of bacteria, cut half a dozen sections with a microtome, and finally resolved the difficulties of seven different gentlemen, who were pursuing researches in as many separate lines of inquiry. Having thus conscientiously and methodically completed the routine of his duties, he returned to his carriage and ordered the coachman to drive him to The Lindens. His face as he drove was cold and impa.s.sive, but he drew his fingers from time to time down his prominent chin with a jerky, twitchy movement.

The Lindens was an old-fashioned, ivy-clad house which had once been in the country, but was now caught in the long, red-brick feelers of the growing city. It still stood back from the road in the privacy of its own grounds. A winding path, lined with laurel bushes, led to the arched and porticoed entrance. To the right was a lawn, and at the far side, under the shadow of a hawthorn, a lady sat in a garden-chair with a book in her hands. At the click of the gate she started, and the Professor, catching sight of her, turned away from the door, and strode in her direction.

"What! won't you go in and see Mrs. Esdaile?" she asked, sweeping out from under the shadow of the hawthorn.

She was a small woman, strongly feminine, from the rich coils of her light-coloured hair to the dainty garden slipper which peeped from under her cream-tinted dress. One tiny well-gloved hand was outstretched in greeting, while the other pressed a thick, green-covered volume against her side. Her decision and quick, tactful manner bespoke the mature woman of the world; but her upraised face had preserved a girlish and even infantile expression of innocence in its large, fearless grey eyes, and sensitive, humorous mouth. Mrs. O'James was a widow, and she was two-and-thirty years of age; but neither fact could have been deduced from her appearance.

"You will surely go in and see Mrs. Esdaile," she repeated, glancing up at him with eyes which had in them something between a challenge and a caress.

"I did not come to see Mrs. Esdaile," he answered, with no relaxation of his cold and grave manner; "I came to see you."

"I am sure I should be highly honoured," she said, with just the slightest little touch of brogue in her accent. "What are the students to do without their Professor?"

"I have already completed my academic duties. Take my arm, and we shall walk in the sunshine. Surely we cannot wonder that Eastern people should have made a deity of the sun. It is the great beneficent force of Nature--man's ally against cold, sterility, and all that is abhorrent to him. What were you reading?"

"Hale's _Matter and Life_."

The Professor raised his thick eyebrows.

"Hale!" he said, and then again in a kind of whisper, "Hale!"

"You differ from him?" she asked.

"It is not I who differ from him. I am only a monad--a thing of no moment. The whole tendency of the highest plane of modern thought differs from him. He defends the indefensible. He is an excellent observer, but a feeble reasoner. I should not recommend you to found your conclusions upon 'Hale.'"

"I must read _Nature's Chronicle_ to counteract his pernicious influence," said Mrs. O'James, with a soft, cooing laugh.

_Nature's Chronicle_ was one of the many books in which Professor Ainslie Grey had enforced the negative doctrines of scientific agnosticism.

"It is a faulty work," said he; "I cannot recommend it. I would rather refer you to the standard writings of some of my older and more eloquent colleagues."

There was a pause in their talk as they paced up and down on the green, velvet-like lawn in the genial sunshine.

"Have you thought at all," he asked at last, "of the matter upon which I spoke to you last night?"