THE DERIVED ALBUMISS. 51 



saturation, the reaction being slightly acid. Most of them, indeed, 

 are thrown down when the salt is added to the extent of 75 

 per cent. Each albumose, in fact, appears to possess certain special 

 limits of precipitation with ammonium sulphate which enables us to 

 separate the individual substances from each other, and also from 

 other albumins which may be present at the same time. Zinc sul- 

 phate behaves in a very similar manner. Sodium chloride when 

 added in substance to saturation causes a partial precipitation of the 

 albumoses from their neutral solutions, while a fairly complete sepa- 

 ration is obtained if to the saturated fluid is added a small amount 

 of acetic acid that has been saturated with the salt. 



Neutral or acid solutions of albumoses are not coagulated by heat 

 nor on treating with alcohol, although they are precipitated when 

 this is present in considerable concentration. After precipitation, 

 however, they are as soluble as before, and in this respect they differ 

 very markedly from the albumins proper. 



Like the native albumins, the albumoses are precipitated by nitric 

 acid, potassium ferrocyanide and acetic acid, metaphosphoric acid, 

 phosphotungstic acid in the presence of hydrochloric acid, tannic 

 acid, picric acid, trichloracetic acid, etc. ; but it must be noted that 

 on the subsequent application of heat the precipitate redissolves, 

 but reappears on cooling. The same result is obtained by treating 

 a solution of albumoses with an equal volume of a saturated solution 

 of sodium chloride and acidifying with acetic acid. 



The Peptones. The term peptone is generally used to designate 

 those final products of albuminous decomposition which result from 

 the albumoses on further digestion with the proteolytic ferments, in 

 so far as they still possess an albuminous character. According to 

 Kiihne and his school, they differ from the albumoses and all other 

 albumins in not being precipitated from their solutions on saturation 

 with ammonium sulphate. Such substances are obtained in abun- 

 dance during the process of tryptic digestion, in vitro at least, while 

 during peptic digestion they are formed only in small amounts and 

 on prolonged exposure to the ferment. 



I have pointed out above, that Kiihne distinguishes between a 

 hemi- and an anti-group in the albuminous molecule, and he accord- 

 ingly divides the peptones into hemipeptone and antipeptone. Both 

 are supposedly formed during peptic as well as pancreatic digestion. 

 In the former instance the mixture of the two substances is spoken 

 of as amphopeptone. It is to be noted, however, that hemipeptone 

 has thus far not been isolated as such, and it appears indeed that the 

 substance is only theoretically existent, and on artificial digestion 

 with trypsin is further decomposed into amido-acids, while in the 

 digestive tract it is supposedly taken up at once by the epithelial 

 cells and transformed into albumin proper. Antipeptone, on the 

 other hand, to judge from recent investigations, represents a mixture 

 of acid and basic substances, among which latter the so-called hexon 

 bases are found. It is thus clear that with the possible exception 



