approximately the same number of tubercle bacilli, but in two of these cows this number of germs was not sufficient to produce infection. Two cows were able to resist and to destroy the limited numbers of tubercle bacilli that entered their bodies. It may be that they would have become infected if the experiment had continued longer. Whether they would have yielded to the attacks of the same number of organisms had they been confined in a badly ventilated, dark stable, is an interesting question. This question cannot be answered by the result of this experiment, because the cows that were confined in the dark, badly ventilated stable were also exposed to more tubercle bacilli, since they were in more direct contact with the diseased cattle that were excreting them.

There can be no doubt, however, that the cows in the light stable were, at the close of the experiment, possessed of more vigor and strength than those in the dark one. This was shown clearly by their bright appearance and the activity and strength of their movements when they were led out of the stable to be weighed.

It is to be observed that the cows in the dark stable put on more weight with the same feed than did those in the light one. The gain made by the four originally healthy cows in the light stable during the experiment was 566 pounds, and the gain made by the four originally healthy cows in the dark stable was 612 pounds. It is common to regard an animal increasing in weight as an animal that is healthy, but that this is not always the case is shown clearly by this experiment, wherein the animals that were most extensively diseased increased in weight more rapidly. This fact comes out very strikingly when we compute the gains made during the different periods of the experiment. During the last period, that is, from June, 1899, to November, 1899, we find that the four originally healthy cows in the light stable gained 212 pounds and the

four originally healthy ones in the dark stable gained 321 pounds. That is, the total gains made by four cows all of which were markedly tubercular was 51 per cent. more than the gains made by four cows fed in the same way and only two of which were tubercular. During the last four months of the experiment the two cows that had contracted tuberculosis in the light stable gained 127 pounds and the two cows remaining healthy in the same stable, receiving the same food, gained 85 pounds.

It seems probable that an animal afflicted with tuberculosis is, in some stages of the disease, more inclined than a healthy animal to lay on fat. This tendency is sometimes marked until a rather advanced stage of the disease.

The question may be asked, could not the disease become latent in the two cows infected in the light stable, in view of their good hygienic surroundings? In answer to this question, it may be said that these conditions were not sufficient to prevent these animals from becoming infected, nor to prevent the disease from reaching a certain and considerable development. There is, therefore, no reason to suppose that the same conditions continued could check the disease after it was well established.

As to what would have occurred if the animals had been given exercise out of doors, we cannot foresee. Of course, it is well known that fresh air is one of the best remedies for consumption. However, the cows in the light stable had plenty of fresh air. They had practically as much oxygen as they could have gotten out of doors and were protected from the weather. The only thing that they were deprived of was exercise. Exercise was not allowed because it was the purpose of the experiment to compare stable conditions, and it was desired to know just what results would follow the stabling together of tubercular and healthy cattle under certain conditions, apart from other influences.

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