PROTEIN SYNTHESIS FROM CLEAVAGE PRODUCTS 63 



ever, upon which there is no unanimity, is to what stage 

 maximal cleavage actually proceeds in physiological condi- 

 tions. Many authors retain the older view "that," as E. 

 Freund 47 says, "the body does not follow a single restricted 

 principle, but manifests a many-sided ability in correspon- 

 dence with the varying demands upon it." "Just as in 

 ordinary household activities there is need not only of small 

 firewood but also of larger timber, so the organism makes 

 use of the protein material in form of all kinds of cleavage- 

 products without first reducing all to the smallest grade." 

 Protein Synthesis from Products of Advanced Cleavage 

 of Protein. The view that all protein undergoes advanced 

 cleavage before resorption assumes the possibility, for main- 

 tenance of the body in nitrogen equilibrium, of its being pro- 

 vided, not with protein, but with the sum total of the lowest 

 products of protein cleavage. The credit of having first 

 experimentally proved this possibility belongs to Otto Loewi. 

 In 1902 Loewi, working in the laboratory of Hans Horst- 

 Meyer, showed experimentally by feeding with pancreatic 

 tissue autolysed to the point of loss of biuret reaction that 

 the aggregate of the biuret-free end-products can 

 be substituted for dietary protein (that is, enters into the 

 composition of every part of the body protein undergoing 

 metabolic disintegration). 48 At first this fundamental 

 proposition was received with widespread doubt ; but later, 

 especially following the experiments of Henriques and Han- 

 sen 49 and, above all, the studies of Abderhalden and his 

 school it has been adopted as beyond doubt. 50 



47 E. Freund., Wiener klin. Wochensehr., 1905, No. 47. 



**O. Loewi ( Pharmacolog. Instit., Marburg), Arch. f. exper. Pathol., 58, 

 303, 1902. 



** V. Henriques and C. Hansen, Zeitschr. f . physiol. Chem., 43, 417, 1904 ; 

 49, 113; 54, 406, 1907. 



M Literature upon the Synthesis of Protein from the Low Protein Cleavage 

 Products: H. Liithje, Ergebn. d. Physiol., 7, 805-830, 1904; P. Rona, Handb. 

 d. Biochem., 4', 540-560, 1910; E. Abderhalden, Synthesis of Cellular Building- 

 stones in Plant and Animal, Berlin, J. Springer, 1912, 128 pp. 



