As a matter of course, under this new and unorthodox arrangement, a dinner invitation at the Keltridges' became a thing of almost infinite value. Apart from the surety of the good dinner, and the cordial welcome of the pretty little hostess who, young as she was, yet understood to the full the delicate distinction between chat and chatter: apart from all this was the humorous question contained within the host. No one could ever foretell whether he would greet them on the threshold in his overcoat and goloshes, or be invisible until the dinner was announced, and then be led in by one cuff, like a guilty youngster caught among the jam pots. No one ever could foretell, either, what would be the doctor's costume for the evening, whether it would combine a dinner jacket and a four-in-hand, or whether a wadded housecoat and no necktie at all above his evening linen would announce to his guests that a sudden thirst for knowledge had cut athwart his dressing and sent him to the laboratory to discover how some malignant brew or other might be getting on. Upon one point only Olive, product of these modern days, stood firm. Her father might be as charmingly erratic as he chose; but he must sterilize his hands, before he came into the drawing-room. And upon that one point of domestic discipline his guests rested in placid confidence, sure that, as long as Olive was at the helm, they could devour the Keltridge dinners in reasonable surety of not being poisoned. If Doctor Keltridge was charming as host, he was even more charming, taken as a father. He was adoring, indulgent, whimsical, and singularly tactful in spite of his absent-minded lapses. To Olive, indeed, he seemed to be the only man at all well worth the while. Nevertheless, as now, it sometimes became imperative to be a little masterful in summoning him back to present consciousness just long enough to extract an answer from him. Therefore she tapped the table sharply with the corner of the note. "Listen, father!" she urged him, as she laid her other hand across the open paper. "What shall I say?" "Say that they are impossible young asses, a year and a half behind the times," her father growled, the while he shifted his paper slightly, to free its final column from her covering fingers. A total stranger to the doctor might have distrusted either his own ears, or else the doctor's sanity. Olive knew her father, though; she felt no forebodings, albeit her eyes danced at the unexpected nature of his response. "I am afraid that Mrs. Dennison might not take it nicely, if I did," she said. The doctor's growl rumbled forth once more. "Better know what one is talking about, then. That theory was all exploded, months ago." Then some echo of his daughter's words seemed at last to be penetrating his brain, and he lowered his paper with a sigh. "What has Mrs. Dennison to do with a thing like this, Olive?" he queried blankly. "Dennison is only history, not biological." Olive laughed outright.