OKIGIN OF FAT IN THE BODY. 365 



a diet containing much albumin, when it is not completely oxidised into C0. 2 , and 

 H 2 0, is the substance from which the fat is formed the latter leaves the body 

 oxidised chiefly to the stage of urea. 



Examples. That fats are formed fi-om proteids is shown by the following : 1. A cow which 

 produces 1 lb. of butter daily does not take nearly this amount of fatty matter in its food, so that 

 the fat would appear to be formed from vegetable proteids. 2. Carnivora giving suck, when 

 fed on plenty of flesh and some fat, yield milk rich in fat.. 3. Dogs fed with plenty of flesh 

 and some fat, add more fat to their bodies than the fat contained in the food. 4. Fatty de- 

 generation, e.g., of nerve and muscle, is due to a decomposition of proteids. 5. The transfor- 

 mation of entire bodies, e.g., such as have lain for a long time surrounded with water, into a 

 mass consisting almost entirely of palmitic acid or adipocere is also a proof of the transforma- 

 tion of part of the proteids into fats. 6*. Fungi are also able to form fat from albumin during 

 their growth. [7. In starving dogs, Bauer estimated the N and C0. 2 given off, and taken in, 

 and then slowly poisoned them with phosphorus, and he found that the excretion of N was 

 increased twofold, while the excretion of C0 2 and the absorption of were diminished one-half. 

 Therefore from a large amount of nitrogenous tissue, a nitrogenous body and a small amount of 

 a carbonaceous compound were excreted, while a large amount of a non-nitrogenous residue was 

 retained unconsumed. There was fatty degeneration of all the organs, the fat being derived 

 from the non-nitrogenous part of the proteid. The same obtains with arsenic and antimony.] 



Fats not merely absorbed. Experiments which go to show that the fat of animals, during the 

 fattening process, is not absorbed as such, from the food, are : 1. Fattening occurs with flesh 

 and soaps ; it is most improbable that the soaps are transformed into neutral fats by taking 

 up glycerin and giving up alkali. 2. If a lean dog be fed with flesh and palmitin- and stearin- 

 soda-soap, the fat of its body contains, in addition to palmitin and stearin, olein fat, so that 

 the last must be formed by the organism from the proteids of the flesh. Further, Ssubotin 

 found that, when a lean dog was fed on lean meat and spermaceti-fat, a very small amount of 

 the latter Was found in the fat of the animal. Although these experiments show that the fat 

 of the body must be formed from the decomposition of proteids, they do not prove that all the 

 fat arises in this way, and that none of it is absorbed and redeposited ( 241, I.). 



III. According to v. Voit, no fat is formed in the body directly from carbo- 

 hydrates, e.g., by reduction. As fattening occurs on a diet of pure flesh with the 

 addition of carbohydrates, it is assumed that the carbohydrates are consumed or 

 oxidised in the body, and that thereby a non-nitrogenous body derived from the 

 proteids is prevented from being burned up, and that it is changed into fat, and 

 stored up as such. No doubt fat is formed indirectly in the blood in this way 

 ( 240). 



From experiments upon fattening animals, however, Lawes and Gilbert, Lehmann, 

 Heiden, v. Wolff, and others, think they are entitled to conclude that the carbo- 

 hydrates absorbed are directly concerned in the formation of fats, a view which is 

 supported by Henneberg, B. Schulze, and Soxhlet. According to Pasteur, glycerin 

 (the basis of neutral fats) may be formed from carbohydrates. 



[Tscherwinsky fed two similar pigs from the same litter ; No. I. weighed 7300 grms. ; No. II. 

 7290 grms. No. I. was killed and its fat and proteids estimated. No. II. was fed for four 

 months on grain and then killed, the grain and excreta and the undigested fat and proteids 

 were analysed, so that the amount of fat and proteid absorbed in four months was estimated. 

 The pig then weighed 24 kilos., it was killed and its fat and proteids estimated. 



No. II. contained 2 "50 kilos, albumin and 9*25 kilos, fat. 



No. I. ,, 0*96 0'69 ,, 



Assimilated, 1'56 ,, ,, 8*56 ,, ,, 



Taken in in food, 7'49 ,, ,, 0*66 ,, ,, 



Difference, -5*93 ,, ,, - +7*90 ,, ,, 



There were therefore 7 '90 kilos, of fat in the body which could not be accounted for in the fat 

 of the food. The 5 "93 kilos, of albumin of the food which were not assimilated as albumin 

 could yield only a small part of the 7*90 kilos, of fat, so that at least 5 kilos, of fat must have 

 been formed from carbohydrate. Lawes and Gilbert calculated that 40 per cent, of the fat in 

 pigs was derived from carbohydrates. How the carbohydrates are changed into fat in the 

 body is entirely unknown.] 



Formerly it was believed that bees could prepare wax from honey alone ; this is a mistake 

 an equivalent of albumin is required in addition the necessary amount is found in the raw 

 honey itself. 



