126 THE PROTEIN SUBSTANCES. 



obtain an alkali albuminate by the action of an alkali upon an acid 

 albuminate; but we cannot obtain an acid albuminate by the reverse 

 reaction (K. MORNER x ) . This does not exclude the possibility that by 

 the action of strong acids products can be obtained which perhaps 

 correspond to those products obtained by the action of less stronger 

 alkali. 



The preparation of the albuminates has been given above. The cor- 

 responding albuminate obtained by the action of alkalies or acids upon 

 aproteid solution maybe precipitated by neutralizing with acid or alkali. 

 The washed precipitate is dissolved in water by the aid of a little alkali or 

 acid, and again precipitated by neutralizing the solvent. If this precipi- 

 tate, which has been washed in water, is treated with alcohol and ether, 

 the albuminate will be obtained in a pure form. 



In the preparation of acid as well as of alkali albuminates, proteoses and the 

 nearly related albuminates are formed. The " alkali albumose " obtained by 

 MAAS 2 belongs to this class. The lysalbinic acid and protalbinic acid obtained 

 by PAAL 3 from ovalbumin are likewise alkali albuminates. Desaminoalbuminic 

 acid is an alkali albuminate which SCHMIEDEBERG 4 obtained by the action of 

 such weak alkali that a part of the nitrogen was evolved but the quantity of 

 sulphur remained the same. The proteid combination obtained by BLUM 5 by the 

 action of formol on proteid and called by him protogen, has similarities with the 

 alkali albuminates in regard to solubilities and precipitation, but is not identical 

 therewith. 



2. Proteoses and Peptones* 



Peptones were formerly designated as the final products of the decom- 

 position of protein bodies by means of proteolytic enzymes in so far as 

 these final products are still true proteins, while the intermediate 

 products produced in the peptonization of proteins, in so far as they are 

 not substances similar to albuminates, were designated as proteoses 

 (albumoses, or propeptones) . Proteoses and peptones may also be 

 produced by the hydrolytic decomposition of the proteins with acids 

 or alkalies, and by the putrefaction of the same. They may also be 

 formed in very small quantities as by-products in the investigations 

 of animal fluids and tissues, and the question as to the extent to which 

 these exist preformed under physiological conditions requires very careful 

 investigation. 



1 Pfliiger's Arch., 17. 



2 Zeitschr. f. physiol. Chem., 30. 



3 Ber. d. d. chem. Gesellsch., 35. 



4 Arch, f . exp. Path. u. Pharm., 39. 



5 Blum, Zeitschr. f. physiol. Chem., 22. The older investigations of Loew may 

 be found in Maly's Jahresber., 1888. On the action of formaldehyde see also Benedi- 

 centi, Arch. f. (Anat. u.) Physiol., 1897; S. Schwarz, Zeitschr. f. physiol. Chem., 30; 

 Bliss and Novy, Journ. of Exper. Med., 4. 



