A second experiment with a dog of 5.8 kilograms, fed on meat, fat, and rice, led to essentially the same results as the preceding experiment At the end of the first month, there appeared indications that the animal was not well, loss of appetite being marked, with disturbance of the stomach accompanied by occasional vomiting. These symptoms disappeared quickly when the animal was given for a few days large quantities of meat. On returning to the original low proteid diet, with its large content of rice, the symptoms gradually reappeared. At the end of two months the animal had again lost its appetite, and before the end of the fifth month the subject was dead. Post-mortem examination showed especially a strong fatty degeneration of the epithelial cells of the mucous membrane of the stomach and intestine. Rosenheim concludes that a diet poor in proteid is unhealthful for dogs, and that a daily ration containing even 0.32 gram of nitrogen per kilogram of body-weight, and with a fuel value of 110 calories per kilo, is not sufficient to maintain the animal in a condition of health.

The next series of experiments was made by Jagerroos1 of Finland. This investigator was evidently impressed by the unfavorable and monotonous character of the diet made use of by the preceding investigators, and sought to introduce a little variety, recognizing also that with a carnivorous animal it is difficult to reduce the proteid to a low level and maintain the necessaiy fuel value, without introducing foodstuffs to which the animal is wholly unaccustomed. In the first experiment, the dog had a body-weight of 5.77 kilograms, and at the beginning was fed daily 40 grams of meat and 100 grams of sugar, equal to 0.31 gram of nitrogen and 80 calories per kilo of body-weight. The experiment continued for eight months, sugar being replaced in part by butter, and occasionally bread, fat, and wheat meal being used in proper amount to yield the given nitrogen and fuel values. During the last five months, the intake of nitrogen per day averaged 0.29 gram per kilo, with a fuel value amounting to 89 calories daily per kilo of body-weight During this period, the animal maintained a plus nitrogen balance for a large part of the time. The experiment was then continued for two months longer, with a gradual diminution in the nitrogen of the food and in the fuel value, the animal dying at the end of the tenth month.

In a second experiment, the dog made use of weighed at the beginning 11.97 kilograms. During the first five months, the average intake of nitrogen amounted daily to 0.29 gram per kilo, while the average fuel value of the food (meat, fat, and sugar) was 76 calories per kilo daily. In the middle of the seventh month the animal was quite ill, with poor appetite, vomiting, etc. Body-weight began to fall off, and the animal soon died. With both of these animals, the experiment ended suddenly by a sharp and short illness.

1 B. H. Jagerroos: Ueber die Folgen einer ausreichenden, aber eiweUsarmen Nahrung. Skandinayisches Archiv fur Physiologie, Band 18, p. 876,1902.

Jagerroos, however, believed that both animals died from a severe case of infection, and not as the result of the diminished intake of proteid. This view was fully substantiated, in his opinion, by the evidence furnished on bacteriological and morphological examination. There was no pathological alteration and no fatty degeneration in the intestinal epithelium; nothing to indicate any connection between the lowered proteid intake and the death of the animal. To be sure, the long-continued diet poor in nitrogen might have diminished the power of resistance of the body, but no proof of this is offered. There was indicated merely a simple infection, as shown by the presence of Streptococcus and Bacterium coli communis in the blood. But, as Jagerroos states, one might well conceive of a lowered power of resistance on the part of the body, due not to any change in diet, but to the long-continued confinement in a cage with the enforced inactivity and lack of freedom. It is to be noted, furthermore, that here there was no sign of a gradual and progressive weakening of the body, no indication of any disturbance of the digestive tract with diminished power of absorption of either fat or proteid. On the contrary, there was asudden and sharp attack of some infectious disease by which the animals quickly succumbed. Jagerroos was of the opinion that in the absence of this infection the animals would have continued to live for a long period of time.

If a low proteid diet works so inimically on high proteid animals as Munk and Rosenheim thought, it would naturally be expected that the small proteid ration followed so long by Jagerroos would have resulted in the appearance of marked symptoms, at least a gradual and persistent falling off in body-weight, inability to maintain nitrogen equilibrium, etc.; but none of these things occurred. In Munk's first experiment, the animal was given no fresh meat whatever during four weeks. Is it not quite possible that in the abrupt cutting off of this wonted form of food a disturbance may have been set up in the gastro-intestinal tract, which paved the way for the more serious results that followed? Jagerroos used only fresh, uncooked meat in his experiments, and laid great stress upon the importance of not departing any more than was necessary from the accustomed form of diet. The writer is strongly of the opinion that sufficient stress has not been laid upon this phase of the subject. A satisfactory diet for dog as for man must meet ordinary hygienic requirements; it must not only be sufficient in amount, but it must be easily digestible, of accustomed flavor, appealing to eye, nostrils, and palate, with reasonable variation occasionally and of moderate volume. With due regard to these conditions, I believe with Jagerroos that not much attention need be paid to the proportion of nitrogen therein, for however small the amount it will be found sufficient to meet the needs of the body.