436 CHEMICAL DISCOVERY AND INVENTION 



results are summarised in the following table, in which the 

 inactive products are marked d I, and the natural active products 

 are recorded separately : 



Glycine 

 Alanine d I 

 ,, d 

 Valine d I 



d 



Leucine d I 



iso Leucine d I 



55 55 ^ 



Phenyl-alanine d I 



5, I 



Serine d I 

 Tyrosine d I 

 Aspartic acid d I 

 Glutamic acid d I 



(Perkin and Duppa, 1858) 



(A. Strecker, 1850) 



(E. Fischer, 1899) 



(Fittig and Clark, 1866) 



(E. Fischer, 1906) 



(Limpricht, 1855 ; E. Schulze and Likiernik. 



1885) 



(E. Fischer, 1900) 

 (Bouveault and Loquin, 1905) 

 (Loquin, 1907) 

 (Erlenmeyer and Lipp, 1883) 

 (Fischer and Scholler, 1907) 

 (Fischer and Leuchs, 1902) 

 (Fischer and Jacobs, 1906) 

 (Erlenmeyer and Lipp, 1883) 

 (Fischer, 1900) 

 (Dessaignes, 1850) 

 (Piutti, 1887) 

 (L. Wolff, 1890) 

 (Fischer, 1899) 

 (R. Willstatter, 1900) 

 (Fischer, 1900) 

 (Sorensen, 1905) 



Proline d I 



Ornithine d I 

 d 



Arginine active ; par- 

 tial synthesis from 

 ornithine (Schulze and Winterstein, 1899) 



Lysine d I (Fischer and Weigert, 1902) 



Tryptophane d I (A. Ellinger and Flamand, 1907) 



Cystine d I (Erlenmeyer, j un., 1903) " 



There can be little doubt that any association of amino-acids 

 could be brought about by application of the existing methods. 

 But to deal with the whole of the proteins will be a gigantic 

 task, and after all it may turn out that the natural proteins do 

 not occur singly, but quite possibly are generated in the living 

 tissue two or more together, and that metabolic changes in the 

 body involve the transformation of several of these complex 

 compounds simultaneously. 



