306 Extracts from the Journals. [Oct., 



fact that the quantity of fat in an animal is by no means always 

 proportional to the quantity he derives from his food, we are led 

 to conclude that the power of producing fat, exists as well in the 

 animal as vegetable world. While oats contain as much as 5.6 

 of fatty matter, turnips contain scarcely any, yet animals speedily 

 fatten on them. Again Boussingault has shown. that in the pro- 

 cess of fattening pigs, more fat is formed than is found in their 

 food. Mulder remarks — "The opinion that fats may readily be 

 produced in the animal body from the food, is strongly supported 

 by the facts that some fats are actually and necessarily produced; 

 for instance, fats of the brain, cholesterin, cetin, and many other 

 peculiar fats. Now, if fats are produced in the animal body, it 

 must be either from other fats, or from other substances, such as 

 starch. Both processes are the same, in so far as in every case 

 there must be a rearrangement of the elements. In a scientific 

 point of view, therefore, there is nothing unlikely in the opinion 

 that animals are able to produce tat." Liebig is another oppo- 

 nent of the doctrine, and brings forward most pow^erful reasoning 

 to support his view of the subject. He considers fat to be pro- 

 duced from the starchy and saccharine matter consumed by ani- 

 mals; all excess of these principles not employed in the produc- 

 tion of heat by the combustion of the constituent carbon in the 

 lungs, is taken into the circulation and converted into fat, being 

 found as such in the blood, and is finally deposited in the fat 

 cells. 



This view accords, in a similar manner, with many well estab- 

 lished facts connected with the feeding of cattle; if an animal is 

 fed with highly azotised food, it becomes full of flesh, especially 

 if at the same time sufficient exercise is taken to consume the car- 

 bonised materials by respiration; but if on the contrary, substan- 

 ces rich in starch or sugar, or other non-azotised principles, are 

 employed for food, little flesh is acquired, but abundance of fat, 

 and this is more particularly the case if rest is enjoined with the 

 use of these materials, inasmuch as by such a plan of proceeding 

 less carbon is employed in the lungs, and more left at liberty to 

 form fat. Thus, then, by placing an individual under circum- 

 stances where he consumes less oxygen, a greater quantity of fat 

 is developed; such circumstances are found in the stall-fed animal 

 where deficient exercise and diminished cooling are equivalent to 

 a diminished supply of oxygen, and less waste is consequently 

 experienced by motion, and increased efforts to preserve the ani- 

 mal temperature. Another interesting fact has been pointed out 

 by Dr. Playfair, that the lungs of the good feeding breed of cattle 

 are of small capacity, giving us this inference, that respiration is 

 in them reduced, as it were, to the smallest capacity. 



It is impossible in short limits to follow Liebig through his 



