Page:Popular Science Monthly Volume 1.djvu/422

408 looked like food that had suffered no change. It is, therefore, only at a late period in such dieting that the absence of the salts makes itself felt.

This was altogether unexpected; but the examination of the excreta, more especially of the urine, led to a conclusion of still greater moment. This urine contains traces only of the chloride of sodium, but little phosphoric acid, etc., although in amount the urine was the same as before the experiment. The residuum of meat which was given was not entirely deprived of its salts. There will always remain a small amount of phosphates. When, therefore, the organism is stinted in these salts, it daily parts with a small quantity of them through the excrement and the urine, but retains the greater part. The organs are tenacious of these salts. When we add salt to the food, it goes first into the blood, but it is not then immediately thrown off by the kidneys, etc. It is distributed through the system, and each one of the organs takes according to its wants. In the blood are also to be found the salts evolved in the destruction of the animal's substance, under the influence of abstinence. All these salts are then distributed, as we have already said, and thus that portion of them which is not thrown off serves again and again for the needs of the tissues. On this account their quantity varies but little in the system. We will not follow our author in his attempt to account theoretically for these phenomena, inasmuch as it belongs to the province of pure reasoning. We must be content to continue in the domain of experiment.

After a period of complete abstinence from salts, certain remarkable phenomena are to be observed in dogs. Though they may not decrease in weight, nor lose flesh or fat, they still become weak, dull, and lie down in a corner, languid and indifferent. On one occasion, even, as in the case of a dog of Dr. Bischoff's that was for a long time fed on bread alone, the animal apparently went mad. He fell into a rage, and ran round and round, heeding neither the voice nor the whip. The attack did not return, but the nervous system became more and more unstrung; paralytic symptoms were manifested in the hinder extremities; the animal's hind-legs failed him at every step, and he fell on his side: in the head were observable oscillatory movements, particularly when he ate or drank. On pushing the experiment still further, the animals invariably succumbed. If, however, instead of continuing the experiment, we give the dog the ordinary mixed food, he will commence gradually to recover his strength, and finally will be quite restored to health. During the period of recovery he will consume an unusual amount of food.

Thus is it demonstrated, in accordance with the views which Liebig was the first to maintain, that the salts are absolutely necessary. Without them the organism fails, even though it were to receive all the other elements. It will not, however, succumb instantaneously, but only after the lapse of a certain period of time. The salts differ