v INTERNAL EESTITUTIVE SECEETIONS 327 



These results were, however, submitted to more rigorous 

 examination by other workers (Klaus, Legert, Athanasiu, Lebedeff, 

 Kosenfeld). They have proved that in so-called fatty degenera- 

 tion, particularly from phosphorus, there is at first not an increase, 

 but a diminution of the total amount of fat in the body. In 

 the majority of organs the amount of fat has not increased, and 

 where it has augmented (liver) this occurs by migration of fat 

 from the adipose tissues. In fact, if a dog has previously been 

 fattened up with mutton suet, the fat extracted from the liver 

 degenerated by phosphorus shows the characteristics of mutton fat. 



That fat can be formed from protein under normal conditions was 

 shown by Pettenkofer and Voif (1862, 1870, 1871), by experiments 

 on dogs kept on a full flesh diet. They estimated the total 

 intake and output of nitrogen and carbon, using as a criterion of 

 the carbohydrate metabolism the carbonic acid exhaled by the 

 animal into the large respiratory apparatus, invented by these 

 authors, of which we shall speak in treating of general metabolism. 

 They found that the whole of the nitrogen from the flesh of the 

 diet is excreted with the urine ; on the other hand, a considerable 

 amount of carbon remains in the body, either in the form of fat 

 (as supposed by the two Munich workers) or in the form of 

 glycogen (as others more correctly assumed). 



Pfliiger, however, who did not admit the derivation of fat from 

 natural protein, succeeded in showing that the carbon of the 

 body was not derived from the proteins introduced, but from the 

 glycogen and fat simultaneously administered. The quotient 

 C/N was calculated too high by Pettenkofer and Voit. This was 

 explicitly recognised in subsequent work by E. Voit, Cremer, 

 Kumagawa. 



Liebig's theory of the derivation of fat from carbohydrates 

 remained unshaken till Voit proposed to explain the fattening of 

 animals by hyperalimentation with carbohydrates, on the theory 

 of "sparers," i.e. by assuming that carbohydrates diminish the 

 normal consumption of fats, which therefore accumulate in the 

 body. 



Later work has, however, shown the earlier theory to be 

 correct, i.e. that the larger part of the fat stored up in the 

 body originates in the carbohydrates. I. Munk (1885) repeated 

 on a dog the experiment of Fr. Hofmann, causing it to 

 consume all its fat in a 31 days' fast, and then nourishing it 

 on a minute amount of flesh and with increasing quantities of 

 starch and sugar. After 24 days the animal was killed, when he 

 found that it contained 960 grms. fat, only 172 grms. of which 

 could be derived from the flesh ingested ; the other 788 grms. 

 could only be formed from the carbohydrates, of which, according 

 to Munk's calculations, 8'3 per cent had been converted into fat. 



N. Tscherwinsky (1883) performed a more rigorous experiment 



