While it should be borne in mind that Albitsky's observations on realimentation and metabolism during undernutrition were incidental to the major study, continuing only 3 or 4 days, and the deductions are thus based upon fragmentary evidence, his final conclusions are that, during realimentation with a diet below maintenance, the metabolism per kilogram of body-weight was at first distinctly lower than normal, but as the undernutrition continued, the metabolism gained in intensity till it more nearly approached the normal. These conclusions are distinctly open to question on account of changes in the amount of food administered during the compared periods.

In contradistinction to Albitsky's conclusions, a statement is made in the dissertation of the younger Pashutin2 that a full-grown rabbit, well fed and in a condition of equilibrium, when gradually deprived of 25 to 50 per cent of its food and the low nutrition continued for some time, showed but little change in the vital processes and general health, so far as could be judged by the body-weight. This paradoxical phenomenon of the actual change in the metabolism of animals under such conditions of reduced diet was confirmed by the younger Pashu-tin's later study in the same laboratory. An apparatus on the closed-circuit principle, devised by Professor V. V. Pashutin, was used for measuring the carbon-dioxide excretion and the oxygen consumption.

In this study, rabbits and subsequently dogs were employed. The plan was ingenious in that the amount of nutriment required for maintenance was first determined and then a certain percentage of the food was gradually withdrawn. The attempt was made in the undernutrition period so to adjust the diet that the loss in body-weight should be less than 15 per cent. This was done on the supposition that degenerative changes in the organs and tissues would appear with a 15 per cent loss in weight or, according to one Russian observer, Okhotin, with a 10 per cent loss. Although the food of the first rabbit was reduced to 85 per cent of the normal requirement, the total carbon-dioxide excretion and oxygen consumption did not change or at least did not exceed normal fluctuations. Since the body-weight of this particular rabbit fell only 6 per cent, it is probable that no definite conclusions can be drawn from the data. With a second rabbit the food was reduced to 67 per cent of the normal needs and the body-weight fell 11 per cent. As a result of these experiments with rabbits, it appeared perfectly possible to reduce the diet considerably with almost inappreciable alteration in the total oxygen consumption. Since the curtailment in diet produced only slow changes in the body-weight and since, in the absence of evidence as to the activity of the animal under observation, it must be assumed that the activity was relatively constant, it follows that the lowered food intake was without appreciable effect upon the metabolism.

1 Another Russian writer, Manassein (Medical Information, 1871), in experiments with animals with complete starvation, also noted a high temperature, which he characterized as febrile. 2 I. A. Pashutin, loc. cit.

In experiments with dogs, Pashutin found that when the diet was reduced to 75 per cent of the normal requirement, neither the oxygen consumption nor carbon-dioxide production was appreciably altered. On the other hand, the period of observation was so short (apparently not far from 2 weeks) that the diet was not sufficiently low to alter materially the body-weight.

A dog, with which observations were begun January 15, was fed for a month with 500 grams of horse flesh daily. Its weight in the middle of February was 6,098 grams. The food was then reduced and 75 per cent of the normal diet given for 19 days, 65 per cent for 29 days, and 55 per cent for 7 days. During the last period the animal fell to a weight 10.6 per cent below the initial weight. He was subsequently fed with 500 grams of meat for 24 days; a second undernutrition period of 33 days with 55 per cent of food followed. Under these conditions it was found that when 75 per cent of food was given, the oxygen consumption and carbon-dioxide excretion fell to about 88 per cent of the normal; it was not until the food was reduced to 55 per cent of the normal diet that the gaseous metabolism fell to approximately 75 per cent. In the realimentation period the gaseous metabolism did not return to the normal amount. In the second undernutrition period the oxygen fell to 71 per cent and the carbon dioxide to 66 per cent of the normal excretion. During the second realimentation period of 23 days with 500 grams of meat the animal gained in weight so that he was 26 per cent above normal. Even under these conditions the oxygen consumption was only 79 per cent of normal and the carbon-dioxide production 74 per cent. With this dog, therefore, it is clear that the reduction in diet was accompanied by a distinct fall in the respiratory exchange, a fall that was not compensated by realimentation, even when the body-weight increased to 26 per cent above normal.

A second dog was brought into equilibrium at a body-weight of 6,221 grams by feeding with an abundance (617 grams) of horse flesh. The food was then reduced to 63.2 per cent of his normal amount. This period of undernutrition continued 23 days. The dog was next fed for 28 days with approximately 3 per cent above the normal amount of food. A second undernutrition period of 22 days followed, in which the food was again reduced to 63.2 per cent. As during the realimentation period the animal had gained in weight to more than 20 per cent and even during the second period of lowered food intake it was 17 per cent above weight,1 the investigator further gradually reduced the food to bring the body-weight to the original point. To do this it was finally necessary to reduce the food to approximately one-third of the normal amount and continue this diet for four weeks. The author concludes from these experiments that the sudden curtailment of food had a much greater effect upon the metabolism than a gradual reduction of food intake. At no period of the realimentation process did the gaseous metabolism exceed normal; in fact, when the food intake was two-thirds that of the normal amount, both the oxygen consumption and carbon-dioxide production approximated 75 to 80 per cent of the normal. During the period of very greatly reduced intake, when the food finally reached but 30 per cent of the maintenance amount, no gaseous metabolism measurements were made.