124 HEMI-ALBUMOSE. [BOOK II. 



From the solution after digestion, acetic acid added to neutralisa- 

 tion, threw down a substance having the characters of antialbumid, 

 and particularly exhibiting the characteristic property of yielding 

 when digested with soda and trypsin a thick jelly. The filtrate from 

 the acetic acid precipitate of antialbumid contained antipeptone, 

 which when digested during eight days at 40 C. with soda 'and 

 trypsin gave no trace of leucin or tyrosin. 



From the solution, antipeptone could be precipitated by concentra- 

 tion arid the addition of alcohol. 



Hemi-albumose and the Albumoses. 



As the reader has gathered from much which has preceded, 

 hemi-albumose is the name which was applied by Klihne to the first 

 product of the action of hydrolytic agents and especially of the 

 proteolytic enzymes, upon the hemi-moiety of the proteid molecule. 

 To the same product the term a. peptone had been assigned by 

 Meissner and propeptone by Schmidt-Mulheim 1 . 



As a result of his earlier researches, Kuhne announced hemi- 

 albumose to be a body sparingly soluble in cold water, more soluble 

 in hot water; precipitable by nitric acid, the precipitate being 

 dissolved on adding an excess of acid, or on heating ; the precipitate, 

 in the latter case, returning when the liquid is allowed to cool. 

 Hemi-albumose was found, further, to be soluble in weak solutions of 

 NaCl, from which it is deposited if the salt be added to saturation. 

 Acetic acid and ferrocyanide of potassium precipitated solutions of 

 hemi-albumose. With copper sulphate and sodium hydrate, hemi- 

 albumose was found to give in an intense degree the 'biuret' reaction, 

 which had been supposed to be characteristic of the true peptones. 



A further, most useful, character of hemi-albumose, a knowledge 

 of which we owe to Wenz 2 , is that of being completely precipitated 

 when its solutions are saturated with ammonium sulphate. This 

 salt affords indeed an easy and certain method of separating peptones 

 from all other proteid substances in a digestive mixture, these being 

 thrown down, whilst the peptones are left in the solution, which 

 then may be freed from the ammoniacal salt by dialysis, or by 

 boiling with barium carbonate or hydrate. 



Even in one of his earlier papers, on the immediate products of 

 decomposition of the proteids, Kuhne had expressed a doubt as to 

 the product which he had termed hemi-albumose being a definite 

 chemical individual. The researches, which he in conjunction with 

 Ohittenden afterwards carried out, proved conclusively that the 

 hemi-albumose which he had first obtained, is a mixture of several 

 bodies, to which they have assigned the names ' proto-albumose,' 

 * deutero-albumose,' ' hetero-albumose ' and ' dys-albumose.' Still it 



1 Schmidt-Mulheim, ' Untersuclmngen iiber d. Verdauimg der Eiweiss-Korper.' Du 

 Bois Reymond, Archiv f. Anat. u. P%*., Phys. Abth. 1879, p. 1. 



2 Wenz, 'Ueber das Verhalten der Eiweissstoli'e bei der Darm-Verdauung.' Zeit- 

 schriftf. Biologie. Bd. 22 (1886), S. 1. 



