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THE POPULAR SCIENCE MONTHLY. 



to contain these soda-salts almost exclusively, while in the urine were 

 found only the salts of potash. The salts of soda thus were altogether 

 retained, as in the case where the salts were withheld. 



It is not the functions of the nutritive salts that have been exag- 

 gerated hitherto, but rather the proportion in which they must enter 

 into the food. They might he withheld for as many as forty days, for 

 they are found in sufficient quantity in all substances which contain 

 the other elements of nutrition. Haubner has stated that pigeons fed 

 on grain, without lime, quickly die ; but Voit has kept them on such 

 food for a whole year. On food deprived of salts a pigeon can live for 

 about thirty days. 



When it is said that, without the nutritive salts, the residuum of 

 meat, or any other kind of food, possesses no nutritive value whatsoever, 

 the statement is true only in a certain sense, and as far as the duration 

 of complete nutrition is concerned. Within a certain period of time, 

 in the absence of the salts, the albuminates will cease to be assimi- 

 lated, as also the fats and the hydrates of carbon. It is the salts that 

 render the organic elements nutritive. The author hence concludes 

 that none of these elements, whether organic or mineral, have any 

 absolute nutritive value, and that they cannot be considered apart by 

 themselves. They cooperate mutually in nutrition, and so are all 

 equally indispensable to constitute proper food, such as may support 

 life and strength. This is the most important datum of the numerous 

 and varied physiological experiments made in Germany during the 

 past few years, and it is a new discovery for us. Our physiologists 

 and hygienists had no suspicion of such facts. 



As we consume, with our food, considerably more of these salts 

 than is needed to support the body, the question arises, Is this simjoly 

 surplus, or are we benefited by it, as being a flavoring for the food ? 

 Much has been said about the extractive elements of meat, and it has 

 been supposed that these elements form the true distinction between 

 animal and vegetable food. According to this view they constitute 

 the peculiar action of meat and of meat-extract. Here we must make 

 a distinction between the nutritive element and the condiment. 



The extractive elements of flesh-meat are the products of regres- 

 sive change, and are not necessary for the constitution and formation 

 of the organs ; nor can they, when taken with food, add to the sub- 

 stance of those organs. The elements of this extract have been got in 

 isolated forms, as creatine, sarkine, taurine, urea, uric acid, tyrosine, 

 lactic acid, acetic acid, etc. ; each organ has its own characteristic 

 extractive principles, or its own products of decomposition, the con- 

 ditions of this decomposition varying for the various organs. 



