446 CHEMISTRY OF THE PROTEIDS CHAP. 



they are boiled with water or with acids, but is also induced by 

 ferments, the so-called ' nucleases.' 



Gumlich, 1 working under Kossel, has shown that nucleic acid 

 dissolves readily in the alkaline intestinal and pancreatic juices. 

 This solution depends, according to Araki, 2 in the conversion of the a- 

 nucleic acid into the b-variety, and is brought about by ferments 

 contained in the trypsin- and erepsin-preparations, and also in the 

 thymus. Iwanoff 3 and Plenge, 4 and Schittenhelm and Schroter 5 

 found similar ferments in bacteria, for Plenge could show their pre- 

 sence in a clear manner, for his solid culture-medium consisting of a 

 sodium -nucleate compound became soluble. This liquefaction is for 

 diagnostic purposes as valuable as is the liquefaction of gelatine. 

 According to Kutscher 6 and Araki the dissociating action of the 

 nucleases of such organs as the thymus, and of bacteria, yeast, etc., 

 does not simply stop at the liquefaction of sodium nucleate, but 

 results in a complete dissociation of the latter. Nucleases play an 

 important part in the autolysis of the meat of fish, according to 

 Schmidt-Nielsen, 7 as they convert the nucleic acid into purin-bases, 

 etc. During metabolism nucleic acid is, without doubt, completely 

 disintegrated, its phosphorus being excreted as phosphoric acid. 8 

 The fate of the pyrimidin- and of the purin-derivatives has not yet 

 been cleared up. 9 Lehmann 10 found that if yeast be kept for some 

 time that all its purin-radicals are converted into xanthin. 



According to Bang, 11 the pancreas-nucleic acid possesses definite 

 poisonous properties, such as that of preventing coagulation, etc. The 

 nucleic acid of wheat-embryos behaves analogously, according to 

 Mendel, Underbill, and White. 12 



1 Gumlich, Zeitschr. f. physiol. Chem. 18. 508 (1893). 



2 T. Araki, ibid. 38. 84 (1903), (here the older literature). 



3 L. Iwanoff, ibid. 39. 31 (1903). 



4 H. Plenge, ibid. 39. 190 (1903). 



5 A. Schitteuhelm and F. Schroter, ibid. 39. 203 (1903). 



6 F. Kutscher, ibid. 32. 50 (1900). 



7 S. Schmidt- Nielsen, Hofmeister's Beitrage, 3. 266 (1902). 



8 P. M. Popoff, Zeitschr. f physiol. Chem. 18. 533 (1893). 



9 H. Steudel, ibid. 32. 285 (1901) ; 39. 136 (1903). 



10 V. Lehmann, ibid. 9. 563 (1885). 



11 J. Bang, ibid. 32. 201 (1901). 



13 L. B. Mendel, F. P. Underbill, and B. White, Amer. Journ. of Physiol. 8. 377 

 (1903). 



