THE PROTEIN SUBSTANCES. 25 



solvent. If this precipitate which has been washed in water is 

 treated with alcohol and ether, the albumiuate will be obtained in a 

 pure form. 



Albumoses and Peptones. Peptones are designated as the final 

 products of the decomposition of albuminous bodies by means of 

 proteolytic enzymes, in so far as these final products are still true 

 albuminous bodies; while we designate as albumoses or propeptones 

 the intermediate products produced in the peptonization of albu- 

 mins in so far as they are substances not similar to albuminates. 



Albumoses and peptones may also be produced by the hydro- 

 lytic decomposition of the albumins with acids or alkalies, also 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 to what extent these exist pre- 

 formed under physiological conditions requires very careful inves- 

 tigation. 



Between the peptones which represent the last splitting prod- 

 ucts and those albumoses which stand closest to the original 

 albumin we have undoubtedly a series of intermediate products. 

 Under such circumstances it is a difficult problem to try to draw a 

 sharp line between the peptone and the albutnose group, and it is 

 just as difficult to define our conception of peptones and albumoses 

 in an exact and satisfactory manner. 



The albumoses have been considered as those albuminous bodies 

 whose solutions do not coagulate on boiling and which, to dis- 

 tinguish them from peptones, were characterized chiefly by the 

 following properties. The watery solutions are precipitated at the 

 ordinary temperature by nitric acid as well as by acetic acid and 

 potassium ferrocyanide, and this precipitate has the peculiarity of 

 disappearing on heating and reappearing on cooling. If a solution 

 of albumoses is saturated with NaCl in substance, the albumoses 

 are partly precipitated in neutral solutions, but on the addition of 

 acid saturated with the salt they completely precipitate.- This pre- 

 cipitate, which dissolves on warming, is a combination of albumose 

 with the acid. 



We formerly designated as peptone that albuminous body which 

 was readily soluble in water and which did not coagulate by heat, 

 whose solutions were precipitated neither by nitric acid, nor by 



