116 HANDBOOK OF PHYSIOLOGY. 



cipitated from its solutions by saturation with sodium chloride. On boil- 

 ing in lime-water it is partially coagulated, and a further precipitation 

 takes place on addition to the boiled solution of calcium chloride, magne- 

 sium sulphate, or sodium chloride. 



Alkali- Album in. If solutions of native-albumin, or coagulated or 

 other proteid, be treated with dilute or strong fixed alkali, alkali-albumin 

 is produced. Solid alkali-albumin (Lieberkiihn's jelly) may also be pre- 

 pared by adding caustic soda or potash, drop by drop, to undiluted egg- 

 albumin, until the whole forms a jelly. This jelly is soluble in an excess 

 of the alkali or in dilute alkalies on boiling. A solution of alkali-albu- 

 min gives the tests corresponding to those of acid-albumin. It is not 

 coagulated 011 heating except after neutralization, as in the case of acid 

 albumin. It is thrown down on neutralizing its solution, except in the 

 presence of alkaline phosphates, in which case the solution must be dis- 

 tinctly acid before a precipitate falls. 



To differentiate between Acid- and Alkali-Albumin, the following 

 metkod may be adopted. Alkali-albumin is not precipitated on exact 

 neutralization, if sodium phosphate has been previously added. Acid- 

 albumin is precipitated on exact neutralization, whether or not sodium 

 phosphate has been previously added. 



Globulins. The globulins give the general proteid tests; are insolu- 

 ble in water; are soluble in dilute saline solutions; are soluble in acids 

 and alkalies forming the corresponding derived-albumin. 



Most of them are precipitated from their solutions by saturation with 

 solid sodium chloride, magnesium sulphate, or other neutral salt. They 

 are coagulated, but at different temperatures, on heating. 



Globulin or Crystallin. It is obtained from the crystalline lens by 

 rubbing it up with powdered glass, extracting with Avater or with dilute 

 saline solution, and by passing through the extract a stream of carbon 

 iodide. It differs from other globulins in not being precipitated by satu- 

 ration with sodium chloride. 



MI/OS hi. The relation of myosin to living muscle will be considered 

 under the head of the physiology of muscle. It may, however, be prepared 

 from dead muscle by removing all fat, tendon, etc., and washing repeatedly 

 in water until the washing contains no trace of proteids, mincing it and 

 then treating with 10 per cent solution of sodium chloride, or similar 

 solution of ammonium chloride or magnesium sulphate, which will dis- 

 solve a large portion into a viscid fluid, which filters with difficulty. If 

 the viscid filtrate be dropped little by little into a large quantity of dis- 

 tilled water, a white flocculent precipitate of rnyosin will occur. 



It is soluble in 10 per cent saline solution ; it is coagulated at 60 C. 

 into coagulated proteid ; it is soluble without change in very dilute acids ; 

 it is precipitated by picric acid, the precipitate being redissolved on 



