52 THE ALBUMINS. 



does not occur; this takes place if salts are present, but it is note- 

 worthy that as a result of the coagulation denaturization has not 

 occurred. For if now the precipitated histon is dissolved by the 

 aid of an acid the solution is neutralized ; the histon (unlike acid 

 albumin) remains in solution and can again be precipitated on 

 boiling. 



Nitric acid precipitates the histons, but unlike the common albu- 

 mins the precipitate dissolves on boiling and reappears on cooling. 

 In this respect they resemble the albumoses. 



The ability of the histons to precipitate other albumins (oval- 

 bumin, casein, serum-globulin) from dilute saline solutions has been 

 mentioned. This reaction, together with the behavior of the histons 

 toward ammonia, and their precipitation by the alkaloidal reagents 

 in neutral media, serve for their recognition and identification. 



The Protamins. The protamins which have been obtained thus 

 far do not occur in the animal body independently, but in combina- 

 tion with certain nucleinic acids. They are described at this place 

 nevertheless, as, like the histons, they represent well-defined chem- 

 ical substances, and can be isolated as such. 



The few known members of the group have all been obtained 

 from the testicles of various fishes : salmin from the salmon, sturin 

 from the sturgeon, clupem from the herring, scombrin from the 

 mackerel, cyclopterin from Cyclopterus lumpus, silurin from Silurus 

 glanus, accipenserin from Accipenser stellatus, cyprinin, a and ft, from 

 Cyprinus carpio, and others. In other animals protamins have not 

 been found. Whether or not RuppePs tuberculosamin (from tubercle 

 bacilli) also belongs to this order is not known. 



According to Kossel, the protamins are albumins of the lowest 

 order, and he assumes that a radicle of this kind forms the nucleus 

 of all the more complex albumins. This assumption primarily was 

 based upon the observation that all protamins yield certain decom- 

 position-products, which are also obtained from the albumins. 

 These products are the diamino-acids arginin, lysin, and histidin 

 (KossePs hexon bases). They are present in the protamins in such 

 large amounts (89-93.3 per cent, of the total nitrogen) that Kossel 

 at first inclined to the view that they alone entered into the con- 

 struction of the protamin molecule. Later studies, however, 

 showed that still other radicles are present. Amino-valerianic 

 acid has thus been found ; so also tyrosin, serin, the tryptophan 

 complex, and in salmin at least a-pyrrolidin-carbonic acid. The 

 protamin molecule thus proved to be more complex than Kossel at 

 first thought, and other investigators accordingly do not share his 

 views regarding the existence of a central nucleus of this order in 

 the complex albumins, to which the di-amino-acids resulting on 

 hydrolysis are referable. It has been shown, moreover, that all 

 three hexon bases cannot be obtained from all albumins. More 

 recently Kossel has modified his conception of the central protamin 

 nucleus. He now regards the simplest protamin nucleus as com- 



