THE FORMATION OF FAT IN THE ANIMAL BODY. 



Sei.ik Soskin, Ph. D. 



The controversy regarding the formation of fat in the animal orgh-uiism 

 began with Liebig, who advanced a theory jnst the opposite of that 

 ordinarily accepted. In 1742 the idea was first advanced by Beccaria, 

 in Bologna, that animals take the substances which form their tissues 

 ready-made from the vegetable kingdom. This theory had many fol- 

 lowers, among others Front, in England, while in France Dumas, a con- 

 temporary of Liebig (1842), is especially worthy of mention. The chief 

 point of the theory was that animal fat was derived from the fat of 

 plants. 



Liebig' disputed this deei^-seated belief. He called attention to the 

 relation of the nitrogenous constituents of food to those of the body, 

 and from the fact that Carnivora consume no sugar, starch, or vegeta- 

 ble gums, drew the conclusion that these substances are not really 

 nutrients — that is, they can not build blood. Further, since tlie nitro- 

 genous constituents of plants and of blood have a similar composition, 

 it follows that the nitrogenous constituents of the food of Herbivora 

 contain the elements necessary for the formation of albumen. 



In normal life processes sugar, starch, and vegetable gums undergo 

 combustion in the organism, and are excreted in the form of carbon 

 dioxid and water. That is, they are really fuel, and serve for the produc- 

 tion of heat. If, however, respiration is hindered by a lack of exercise 

 or a rise in temperature, fat accumulates in the organism of Herbivora. 

 Fat must have its origin in the nitrogen-free nutrients. Their carbon 

 remains in the body in the form of fat when there is not enough oxygen 

 to burn it to carbon dioxid. 



Such was Liebig's new theory. The phenomena of fermentation and 

 decay seemed to strengthen it, as did also the discovery by Huber and 

 Gundlach that bees make w^ax when fed on wax-free honey. The 

 theory was further strengthened by the discovery by physicians that a 

 formation of fat followed the consumption of food ricli in sugar, starch, 

 and similar substances, and also by the observation of farmers in fat- 

 tening animals with rice, maize, peas, lentils, potatoes, and turnips. 



Liebig attempted by the aid of statistics to overturn the theory of 

 Dumas and Boussingault that animals take the substances used in the 

 formation of tissue ready-made from the vegetable kingdom. 



»Ann. Cbem. und Pliarm., 45 (1843), p. 112. 



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