408 THE POPULAR SCIENCE MONTHLY. 



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 ex 

 creta, 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 stint- 

 ed 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 kid- 

 neys, 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 remark- 

 able 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 tne 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 



