It is scarcely to the credit of our species that for convincing, actual demonstrations of what can be done toward stamping out tuberculosis, by measures directed against the bacillus alone, we are obliged to turn to the lower animals. By a humiliating paradox we are never quite able to put ourselves under those conditions which we know to be ideal from a sanitary point of view. There are too many prejudices, too many vested interests, too many considerations of expense to be reckoned with. But with the lower animals that come under our care we have a clear field, free from obstruction by either our own prejudices or those of others. In this realm the stamping out of tuberculosis is not merely a rosy dream of the future but an accomplished fact, in some quarters even an old story. Two illustrations will suffice, one among domestic animals, the other among wild animals in captivity. The first is among pure-bred dairy cattle, the pedigreed Jerseys and Holsteins. No sooner did the discovery of the bacillus provide us with a means of identification, than the well-known "_perlsucht_" of the Germans, or "grapes" of the English veterinarians--both names being derived from the curious rounded masses or nodules of exudate found in the pleural cavity and the peritoneum (around the lungs and the bowels), and supposed to resemble pearls and grapes respectively--were identified as tuberculosis, and cows were found very widely infected with it. This unfortunately still remains the case with the large mass of dairy cattle. But certain of the more intelligent breeders owning valuable cattle proceeded to take steps to protect them. The first step was to test their cows with tuberculin, promptly weeding out and isolating all those that reacted to the disease. It was at first thought necessary to slaughter all these at once. But it was later found that, if they were completely isolated and prevented from communicating the disease to others, this extreme measure was necessary only with those extensively diseased. The others could be kept alive, and if their calves were promptly removed as soon as born, and fed only upon sterilized or perfectly healthy milk, they would be free from the disease. And thus the breeding-life of a particularly valuable and high-bred animal might be prolonged for a number of years. They must, however, be kept in separate buildings and fields, and preferably upon a separate farm from the rest of the herd.