ACTION OF LIVER IN METABOLISM OF FATS. 935 



That fat is formed from proteid, although not in the exclusive form in 

 which Voit at one time was disposed to assert, has been almost universally 

 accepted by physiologists ; but this view has been strenuously attacked of late 

 by Pfliiger 1 who has criticised the conclusions drawn by Voit from his experi- 

 ments of feeding dogs upon meat, and has shown that in all probability the meat 

 employed contained sufficient fat to account for the fat laid on in the body with- 

 out supposing this to have been derived from proteid. In a dog kept by himself 

 and fed upon a large quantity of meat containing the least possible fat, no fat 

 whatever appeared to be laid on ; but what was originally present disappeared, 

 so that the dog, although muscular and capable of performing severe work, 

 was reduced to a condition of extreme leanness. Pfliiger is therefore disposed 

 to deny altogether the formation of fat in the animal body from proteid, 2 and 

 considers that its sources are to be looked for exclusively in the fats and 

 carbohydrates of the food. 3 



In this it would appear probable that Pfliiger has gone as much to 

 the one extreme as Voit originally went to the other. It is unquestionable 

 that certain forms of bioplasm are capable of transforming proteid into fat 

 (as in the instances cited on p. 933). This is, in fact, admitted by Pfliiger, who, 

 however, contends that we have no right to assume that other forms of 

 bioplasm, such as that of the cells of the higher animals, possess the same 

 power. He is disposed to regard the change as due in all the cases cited to 

 the action of bacteria and fungi, such as would undoubtedly be present in 

 ripening cheese, in putrefying blood, in putrefying flesh, and the like. But it 

 has been shown that in flesh kept in milk of lime, and therefore under con- 

 ditions unfavourable to the growth of bacteria, fatty acids are still found to a 

 small extent, at the expense of the proteid; and the production of fatty degenera- 

 tion in the cells of starved animals, to which phosphorus has been adminis- 

 tered, is strong evidence in favour of their possessing such a power of forming 

 fat from proteid; these, taken in conjunction with the numerous other instances 

 which have been cited, appear to indicate that this power of forming fat 

 from proteid is a general property of bioplasm. 



As regards the ultimate fate of .fat, there seems to be no doubt that it 

 becomes oxidised into carbon dioxide and water, thus producing energy which 

 may take the form of either heat or work, and that this oxidation takes place 

 mainly in the muscular tissue. 



Action of the liver in connection with the metabolism of fats. 

 Very little is known on this question beyond the fact that, under certain 

 circumstances, there is a considerable accumulation of fat in the liver 

 cells. This has been held by Pavy 4 to indicate the correctness of his 

 view, that fat may be formed both in the liver and elsewhere by the 

 direct transformation of glycogen. But it has not been shown that the 

 glycogen and fat have any vicarious relation to one another ; indeed, the 

 contrary was found to be the case by Langley 5 and by Noel Paton. 6 

 Nevertheless, Paton's experiments show a marked increase in the fatty 



1 Arch.f. d. ges. Physiol. t Bonn, 1892, Bd. li. S. 229 ; ibid., 1892, Bd. lii. S. 1 and 239. 



2 Kumagawa and Kaneda, Mitth. a. d. med. Fac. d. Tc.-jap. Univ., Toldo, 1894, Bd. iii. 

 (abstr. in Centralbl. f. Physiol., Leipzig u. Wien, 1895, S. 721), were also unable to obtain 

 evidence of fat formation in dogs fed upon food consisting almost exclusively of proteid. 



3 For a reply to Pniiger's criticisms, see E. Voit, Munchen. mcd. Wchnschr., 1892, 

 S. 460, and Ztsclir. f. BioL, Munchen, 1896, Bd. xxxii. S. 139; also Cremer, ibid., 1897, 

 S. 811. Pfliiger's answer to these is in Arch. f. d. ges. Physiol., Bonn, 1897, B. Ixviii. 

 S. 176. See also on this subject, I. Munk. Arch.f. d. ges. Physiol., Bonn, 1894, Bd. Iviii. 

 S. 309 ; also Berl. Idin. Wchnschr., 1889, No. 9. 



4 " Physiology of Carbohydrates," p. 258. 



5 Proc. Roy. Soc. London, 1882, vol. xxxiv. p. 20 ; and 1885, vol. xxxix. p. 234. 



6 Journ. Physiol., Cambridge and London, 1896, vol. xix. p. 167. Langley's state- 

 ments are founded upon microscopical observations (in the frog) ; Paton's, upon chemical 

 evidence. 



