The one bright spot in the early days of the battle was Public School Number Three which the twins and Bettina attended. The medical inspector who had this assignment was young, intelligent, and an enthusiast. Backed by Dr. Strong, and effectively aided by the Clyde children, he enforced a system which brought prompt results. In every instance where a pupil was sent home under suspicion,—and the first day’s inspection brought to light three cases of incipient diphtheria, and fifteen which developed into measles, besides a score of suspicious symptoms,—Julia, or Robin Clyde, or one of the teachers went along to deliver printed instructions as to the defense of the household, and to explain to the family the vital necessity of heeding the regulations until such time as the physician could come and determine the nature of the ailment. Within a week, amidst growing panic and peril, Number Three was standing like an isle of safety. After that time, not a single new case of either disease developed from exposure within its limits, and in only two families represented in the school was there any spread of contagion. “It’s the following-up into the house that does it,” said Dr. Strong, at an early morning meeting of the Household Protective Association (he still insisted on occasional short sessions, in spite of the overwhelming demands on his time and energies, on the ground that these were “the only chances I get to feel the support of full understanding and sympathy”), “that and the checking-up of the three carriers we found.” “What’s a carrier?” asked Bettina, who had an unquenchable thirst for finding out things. “A carrier, Toodlekins, is a perfectly well person who has the germs of disease in his throat. Why he doesn’t fall ill himself, we don’t know. He can give the disease to another person just as well as if he were in the worst stages of it himself. Every epidemic develops a number of carriers. One of the greatest arguments for inspection is that it brings to light these people, who constitute the most difficult and dangerous phase of infection, because they go on spreading the disease without being suspected. Now, I’ve got ours from Number Three quarantined. If I could catch every carrier in town, I’d guarantee to be in control of the situation in three weeks.” “Our reports show over twenty of them discovered and isolated,” said Mrs. Clyde, who had turned her abounding energies to the organization of a corps of visiting nurses. “Perhaps I’d better say something about carriers in my next talk,” said Grandma Sharpless, whose natural gift as a ready and convincing speaker, unsuspected by herself as well as her family until the night when she had met and routed the itinerating quack on his own platform, was now being turned to account in the campaign for short talks before Sunday schools and club gatherings.