The girl smiled her gratitude.

“You are very kind indeed, Mr. Quest,” she said simply.  “I will be here.”

The Professor laid his hand upon her arm as she passed.  He had been watching her with curious intentness.

“Young lady,” he observed, “you seem very much in earnest about your work.”

“It is only the people in earnest, sir,” she answered, “who can do any good in the world.  My work is worth being in earnest about.”

“Will you forgive an old man’s question?” the Professor continued.  “I am one of the men of the world who are in earnest.  My life is dedicated to science.  Science is at once my religion and my life.  It seems to me that you and I have something in common.  You, too, move in the unusual ways.  Your life is dedicated to doing good amongst the unworthy of your sex.  Whether my brain approves of your efforts or not, you compel my admiration—­my most respectful admiration.  May I, too, be permitted?”

He drew out a pocket-book and passed over towards her a little wad of notes.  She took them without a moment’s hesitation.  Her eyes, as she thanked him, were filled with gratitude.

“It is so kind of you,” she murmured.  “We never have any hesitation in accepting money.  May I know your name?”

“It is not necessary,” the Professor answered.  “You can enter me,” he added, as he held open the door for her, “as a friend—­or would you prefer a pseudonym?”

“A pseudonym, if you please,” she begged.  “We have so many who send us sums of money as friends.  Anything will do.”

The Professor glanced around the room.

“What pseudonym shall I adopt?” he ruminated.  “Shall I say that an oak sideboard gives you five hundred dollars?  Or a Chippendale sofa?  Or,” he added, his eyes resting for a moment upon the little box, “a black box?”

The two girls from the other side of the table started.  Even Quest swung suddenly around.  The Professor, as though pleased with his fancy, nodded as his fingers played with the lid.

“Yes, that will do very nicely,” he decided.  “Put me down—­’Black Box,’ five hundred dollars.”

The girl took out her book and began to write.  The Professor, with a little farewell bow, crossed the room towards Quest.  Lenora moved towards the door.

“Let me see you out,” she said to the girl pleasantly.  “Don’t you find this collecting sometimes very hard work?”

“Days like to-day,” the girl replied, “atone for everything.  When I think of the good that five hundred dollars will do, I feel perfectly happy.”

Lenora opened the door.  Both girls started.  Only a few feet away Craig was standing, his head a little thrust forward.  For a moment the quiet self-respect of his manner seemed to have deserted him.  He seemed at a loss for words.

“What do you want?” Lenora demanded.

Craig hesitated.  His eyes were fixed upon the Salvation Army girl.  The changes in his face were remarkable.  She, however, beyond smiling pleasantly at him, gave no sign of any recognition.