NITROGENOUS ORGANIC CELL-CONSTITUENTS. 99 



addition of an alkali and then subjected to heat, the acid albumen so 

 suspended in water becomes coagulated, and is then indistinguishable 

 from any other coagulated proteid. After precipitation by neutrali- 

 zation, if the precipitate be then dissolved in lime-water, its solution in 

 lime-water will be coagulable on boiling. Acid albumen is precipitated 

 out of its solution by the neutral salts, such as sodium chloride, and by 

 gallic acid and metallic salts. 



The conversion of albumen into acid albumen from the action of a 

 dilute acid is a gradual process. If a solution of egg-albumen be acidu- 

 lated with dilute hydrochloric acid, and subjected to a temperature of 

 about 40 C., it will be found, if tested from time to time, that a coagulum 

 still occurs on boiling. The amount of proteid so coagulated by heat 

 will steadily decrease, and the amount of precipitate obtained by neutral- 

 ization will increase correspondingly. After only ten or fifteen minutes it 

 will be found that if the solution of acid albumen is exactly neutralized 

 all the albumen will have been converted into acid albumen, and if 

 the precipitate is then filtered off and the filtrate tested with the various 

 proteid tests it will be found that all the proteid has apparently disap- 

 peared ; or, in other words, has been converted into acid albumen. 



A certain degree of temperature is necessary for this conversion. 

 If a mixture of albumen solution and dilute acid be surrounded by ice, 

 the process of conversion into acid albumen will be extremely slow. If 

 warmed up to about 40 C., or, in fact, any distance below the tempera- 

 ture of coagulation of the albumen, the process of conversion will be 

 very much more rapid. 



If finely-chopped muscle is washed in water so as to remove all the 

 soluble albuminous bodies and blood, and the remainder be covered with 

 a large quantity of dilute hydrochloric acid (0.2 per cent.), and kept for 

 about twenty-four hours at a temperature of 40 C., it will be found that 

 the greater part of the muscle will be dissolved ; if the supernatant fluid be 

 filtered off and neutralized, an abundant precipitate of acid albumen will 

 be thrown down in flocculi, which will gradually settle. The acid 

 albumen in this case is derived from the.n^osin of the muscle, and 

 indicates that the globulins as well as the albumens are capable of being 

 converted into derived acid albumen. Acid albumen so obtained from 

 muscle is frequently spoken of as S3'ntonin, but is apparently identical 

 in its general behavior under the different tests to the acid albumen 

 derived from either egg- or serum-albumen. So also in the preliminary 

 stages of gastric digestion of proteids a product is first formed which 

 appears to be identical in character with acid albumen, or syntonin, and 

 is termed parapeptone. It also is precipitated from its solutions by 

 neutralization, and is apparently formed solely through the action of the 

 acid of the gastric juice on proteids. 



