PRIMARY DISSOCIATION-PRODUCTS 29 



glycocoll, according to Pick : and E. Fischer and Abderhalden, 2 is only 

 contained in the 'anti-group' of albumins (see below). The occurrence 

 of glycocoll in globin (asserted by Spiro, 3 denied by Abderhalden 4 ) and 

 in silk glue 5 is questionable. Glycocoll, as already mentioned, is also 

 called glycin, and its derivatives, such as glycylglycin 6 and others, 

 having become of the greatest importance for investigations bearing on 

 the constitution of albumins, are dealt with more fully on pp. 115-137. 

 On being oxidised with manganese dioxide and sulphuric acid it gives 

 rise to prussic acid as first observed by Liebig in 1849. 7 Quite recently 

 this question has been thoroughly investigated by Aders Plimmer 

 (see p. 86). 



The physiology of glycocoll is discussed on p. 108. 



2. Alanin, or Amino-propionic Acid, C 3 H 7 N0 2 

 H NH 



L 2 y^ 

 H C C C v 



H H X OH, 



is a-amino - propionic acid. It used to be believed that alanin was 

 only present in some albuminoids, as, e.g., in the fibroin of silk, 8 but 

 E. Fischer 9 has shown it to be widely distributed, and he attributes 

 its former non-discovery to its great solubility. The aromatic deriva- 

 tives of alanin, namely, phenylalanin, and especially tyrosin or 

 oxyphenyl-amino-propionic acid, have been known for a long time, and 

 the mother substance of the iridol radical of albumins is also an 

 alanin derivative. Serin and cystin are other alanin derivatives. 



The alanin occurring in proteids is d-alanin. 10 Its specific rotation 

 in strong hydrochloric acid, according to E. Fischer, 10 is 



a2o= +9-68. 

 By treatment with nitrous acid it is converted into d-lactic acid, 11 



1 E. P. Pick,' Zeitschr. f. physiol. Chem. 28. 219 (1899). 



2 E. Fischer and E. Abderhalden, ibid. 39.*81 (1903). 



3 K. Spiro, ibid. 28. 174 (1899). 4 E. Abderhalden, ibid. 37X484 (1903). 



5 E. Fischer and A. Skita, ibid. 35. 221 (1902). 



6 Fischer and Fourneau have given the term glycyl to the radical NH 2 * CH 2 CO, 

 glycin or glycocoll being NH 2 CH 2 COOH. 



7 J. Liebig, Ann. Chem. Pharm. 120, 311 (1849). 



8 Th. Weyl, Ber. d. deutsch. chem. Ges. 21. II. 1407 and 1529 (1888). 



9 E. Fischer, Zeitschr. f. physiol. Chem. 33. 151 (1901) ; see also tables, pp. 70 

 to 75, and the other quoted papers by Fischer and his pupils, p. 20, 



10 E. Fischer, Ber. d. deutsch. chem. Ges. 32. II. 2451 (1899) ; E. Fischer, P. A. 

 Levene, and R. H. Aders, Zeitschr. f. physiol. Chem. 35. 70 (1902). 



11 Lactic acid occurs in the form of the two isomers : 



a-oxy-propionic acid or CH 3 CHOH COOH 

 /3-oxy-propionic acid or CH 2 (OH; CH 2 COOH. 

 The a-oxy-propionic acid, if formed by ordinary fermentation, is racemised, i.e. it 



