THE NATIVE ALBUMINS. 41 



C Nucleins. 



Theproteids J Nucleoproteids. 



I (jrlucoproteicls. 

 ^ Haemoglobins. 



C Keratins. 



The albuminoids <J Albumoids. 



(^ Amyloids. 



The derived albumins 



Albumoses. 

 Peptones. 



-P 



11) 



Albuminates. 

 Coagulated albumins. 

 Fibrin. 



THE NATIVE ALBUMINS. 



These have been described in a general way in the foregoing 

 pages. They are subdivided as above indicated. 



The Albumins. The albumins, in the narrower sense of the 

 term, comprise serum-albumin, egg-albumin, lactalbumin, and the 

 so-called vegetable albumin. They are all soluble in water, but may 

 be precipitated from their neutral aqueous solutions by salting with 

 ammonium sulphate. Sodium chloride and magnesium sulphate 

 cause their precipitation only if the solution has been acidified with 

 acetic acid. The addition of small amounts of acids or alkalies to 

 their aqueous solutions is without effect. Larger amounts of mineral 

 acids, as also the salts of the heavy metals, cause their precipitation. 

 Coagulation occurs on boiling, and in the presence of a certain 

 amount of neutral salts, while this does not occur if the solution 

 contains only a trace of salts. 



The albumins of this order are very rich in sulphur, containing 

 from 1.6 to 2.2 per cent. The nitrogen is held in part as so-called 

 amido-nitrogen, partly as diamino-nitrogen, and partly as mono- 

 ammo-nitrogen. 



The Globulins. These comprise serum-globulin, fibrinogen, 

 fibrinoglobulin, myosin, and various vegetable globulins. They are 

 all soluble in dilute solutions of the neutral salts, and may be pre- 

 cipitated from these solutions by saturation with magnesium sul- 

 phate or by 50 per cent, saturation with ammonium sulphate. 

 Sodium chloride precipitates them only in part. Some of them are 

 insoluble in water, while others are soluble without difficulty. If a 

 dilute saline solution of the common serum-globulin of the blood- 

 plasma, for example, is subjected to dialysis, a certain portion of the 

 globulin is precipitated. Another portion, however, remains in 

 solution, and may be demonstrated by saturating with magnesium 

 sulphate or by saturation with 50 per cent, ammonium sulphate. It 



