bb ALBUMINOUS MATTERS. 



present in small quantity in the lymph and in the chyle. It is this sub- 

 stance which is distinguished by its property of " spontaneous coagula- 

 tion ;" that is, it coagulates on being withdrawn from the vascular 

 system, without the addition of any physical or chemical reagent. It 

 is the coagulating element of the blood ; and the power of freshly drawn 

 blood to form a clot depends upon its presence as an ingredient of the 

 circulating fluid. The term fibrine properly represents, hot the solid 

 clot obtained by coagulation, but the fluid substance existing before- 

 hand in the blood, and which becomes solidified after its withdrawal. 

 It is regarded by some as generated by the union of two pre-existing 

 substances ; by others, as produced from the decomposition of one. As 

 we have, however, but little opportunity of studying it while still forming 

 a part of the fluid plasma, our knowledge is mainly confined to its pro- 

 perties in the solidified form. It is obtained by stirring the freshly 

 drawn blood with glass rods or a bundle of twigs, and afterward washing 

 the deposited clots with distilled water until the adherent coloring 

 matter is removed. 



Coagulated fibrine is a colorless, tolerably firm, extensible, and 

 elastic substance, which has, under the microscope, a finely fibrillated 

 texture. It is insoluble in water, but in solutions of the caustic alkalies 

 or the alkaline carbonates it becomes gelatinous, and is after a time, by 

 the aid of warmth, partially dissolved. Some of the free acids, as hydro- 

 chloric, acetic, lactic, or phosphoric acid, have a similar effect. If it be 

 heated in water or in a neutral liquid to 72 (162 F.), it becomes con- 

 tracted, white, and opaque, and less extensible than before. 



An albuminous matter very similar in its physical properties to animal 

 fibrine, exists in certain vegetable substances, especially in wheat flour, 

 where it is known as gluten. When freed from the admixture of other 

 ingredients, it is tenacious, extensible, elastic, insoluble in water, and 

 slowly soluble in dilute alkalies. Its property of tenacity and its 

 nitrogenous character make it an important constituent of wheat flour 

 in the manufacture of bread. 



Albumen. 



Albumen is found abundantly in the plasma of the blood, also in the 

 lymph, the pericardial and cephalo-rachidian fluids, and in very small 

 quantity in the saliva and in the milk. It is not spontaneously coagu- 

 lable, but coagulates promptly when heated in its liquid form to a 

 temperature of 72 (162 F.), and its coagulum is again soluble in the 

 caustic alkalies. It is also coagulated by contact with nitric or sul- 

 phuric acid, alcohol, or the metallic salts. The organic acids, as acetic, 

 lactic, or tartaric acid, do not affect it ; but if it be first slightly acidu- 

 lated by dilute acetic acid, it may be precipitated by a solution of 

 potassium ferrocyanide. This is one of the most delicate tests for the 

 presence of albumen, but it is usually recognized from its coagulability 

 by heat and nitric acid. When dissolved in a fluid of neutral reaction, 

 it rotates the plane of polarization to the left 56. 



