98 PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



being soluble in excess of alkali or acid ; that is, the myosin has been 

 converted into a proteid having the properties of an albuminate. If 

 the saline solution of myosin be placed in an incubator at a temperature 

 of 35° to 40°, in twelve to eighteen hours a fine floeculent precipitate 

 falls, while the globulin disappears from the solution ; this takes place 

 more rapidly if the saline solution is diluted. The precipitate exhibits 

 the same properties as the precipitate of the globulin by dialysis ; that 

 is, at a temperature of 35° to 40° the globulin is transformed into an albu- 

 minate. The ready transformation of the soluble globulin of wheaten 

 flour into an insoluble albuminate is one of the phenomena which take 

 place during the formation of gluten. 



The second class of vegetable globulins, the paraglobulins, is in dis- 

 tinct contrast with that of the myosins. Two proteids of this class 

 have been found, one in papaw-juice, the other in the seeds of Abrus 

 precatorius (jequirity). Both these globulins exhibit the following 

 properties : they are soluble in saline solutions, and are precipitated by 

 saturation with sodium chloride and magnesium sulphate. In a 10 per 

 cent, solution of magnesium sulphate, they coagulate between 70° and 

 75° C. When precipitated from their saline solutions by dialysis, they are 

 still soluble in solutions of sodium chloride and magnesium sulphate of 

 10 to 15 per cent., not being transformed into albuminates. Nor are 

 they precipitated by long exposure (over three days) to a temperature 

 of 35° to 40°. 



III. Fibrins. — Fibrins are solid albuminous bodies insoluble in 

 water and sodium chloride, and which swell up to a stiff jelly in dilute 

 acids. When so treated fibrin is coagulable by heat. The fibrin of the 

 blood is produced in the process of coagulation of the blood ; its prop- 

 erties will be studied with the subject of blood coagulation. 



IV. Derived Albuminates. — Derived albuminates are bodies which 

 are insoluble in water or sodium chloride solutions, but are readily soluble 

 in dilute acids or alkalies. Their solutions are not changed by heat. 

 When neutralized they are precipitated from their solutions, the pre- 

 cipitate being soluble in excess. Derived albuminates may exist in two 

 different forms, — acid albumens and alkali albumens. 



1. Acid Albumen. — When a native albumen in solution is subjected 

 to the action of a dilute acid, such as hydrochloric acid, at a tolerably 

 warm temperature its solutions readily lose their power of coagulating 

 when boiled. If, however, the acid is exactly neutralized by the addition 

 of any alkali the albumen is at once precipitated, and the precipitate is 

 again redissolved by an excess of alkali. The native albumen is thus 

 converted into a form of albuminous body which has become insoluble in 

 water and uncoagulable by heat. 



When acid albumen is precipitated out of its solution by the 



