502 NATIVE ALBUMINS AND GLOBULINS. 



249. The Animal Proteids and their Characters. 



They have been divided into classes: 



Class I. Native Albumins. 



Native Albumins occur in a natural condition in the solids and fluids of the 

 body. They are soluble in water, and are not precipitated by alkaline carbonates, 

 NaCl, or by very dilute acids. Their solutions are coagulated by heat at 65-73C. 

 Dried at 40C., they yield a clear yellow amber-coloured friable mass, "soluble 

 albumin" which is soluble in water. 



(1.) Serum-albumin, whose cheinico-physical characters are given at p. 49, 

 and its physiological properties at 41. Almost all its salts may be removed 

 from it by dialysis, when it no longer coagulates with heat (Schmidt). It is 

 coagulated by strong alcohol, and is easily dissolved in strong hydrochloric acid. 

 When precipitated, it is readily soluble in strong nitric acid. It is not coagulated 

 when shaken up with ether. The addition of water to the hydrochloric solution 

 precipitates acid-albumin. 



(2.) Egg-albumin. When injected into the blood-vessels or under the skin, or 

 even when introduced in large quantity into the intestine, part of it appears 

 unchanged in the urine (p. 397). When shaken with ether, it is precipitated. 

 These two reactions serve to distinguish it from (1). The specihc rotation is 

 37-8. 



(Metalbumin and Paralbumin have been found by Scherer in ropy 

 solutions in ovarian cysts; they are only partially precipitated by heat. The 

 precipitate thrown down by the action of strong alcohol is soluble in water. 

 They are not precipitated by acetic acid, by acetic acid and potassium ferro- 

 cyanide, by mercuric chloride, or by saturation with magnesium sulphate. Con- 

 centrated sulphuric acid and acetic acid give a violet colour (Adamkiewicz). 

 According to Hammarsten, metalbumin is a mixture of paralbumin and other 

 proteid substances. On being boiled with dilute sulphuric acid they yield a 

 reducing substance (? sugar)). 



Class II. Globulins. 



They are native proteids, which are insoluble in distilled water, but are soluble 

 in dilute saline solutions, sodium chloride of 1 per cent., and in magnesium sulphate, 

 These solutions are coagulated by heat, and are precipitated by the addition of a 

 large quantity of water. Most of them are precipitated from their sodium chloride 

 solution by the addition of crystals of sodium chloride, and also by saturating 

 their neutral solution at 30 with crystals of magnesium sulphate. When acted 

 upon by dilute acids, they yield acid-albumin, and by dilute alkalies, alkali- 

 albumin. 



(1.) Globulin (Crystallin) is obtained by passing a stream of C0 2 through a 

 watery extract of the crystalline lens. 



(2.) Vitellin is the chief proteid in the yolk of egg. It is also said to occur 

 in the chyle (?) and in the amniotic fluid (Weyl). Both of the foregoing are not 

 precipitated from their neutral solutions by saturation with sodium chloride. 



(3.) Para-globulin or Serum-globulin (p. 44). 



(4.) Fibrinogen (p. 45). 



(5.) Myosin is the chief proteid in dead muscle. Its coagulation in muscle 

 post mortem constitutes rigor mortis. If muscle be repeatedly washed and after- 

 wards treated with a 10 per cent, solution of sodium chloride, it yields a viscid 

 fluid which, when dropped into a large quantity of distilled water, gives a white 

 flocculent precipitate of myosin. It is also precipitated from its NaCl solution 

 by crystals of NaCl. For Kiihne's method of preparation, see Muscle. 



(6.) Globin (Preyer), the proteid residue of haemoglobin. 



