PLASMA. 



223 



8.55 



PLASMA. The plasma of the blood, according to Lehmann, has 

 the following constitution : 



COMPOSITION OF THE PLASMA i>* 1,000 PARTS. 



Water 902.90 



Fibrin 4.05 



Albumen 78.84 



Fatty matters 1.72 



Undetermined (extractive) matters ...... 3.94 



Chloride of sodium '. 



potassium .... 



Phosphates of soda and potassa . 

 Sulphates " "... 



Phosphate of lime ..... 



magnesia .... 



1000. 00 



The above ingredients are all intimately mingled in the blood- 

 plasma, in a fluid form, by mutual solution; but they may be sepa- 

 rated from each other for examination by appropriate means. The 

 two ingredients belonging to the class of organic substances are the 

 fibrin and the albumen. 



The fibrin, though present in small quantity, is evidently an Jm- 

 portant element in the constitution of the blood. It may be ob- 

 tained in a tolerably pure form by gently stirring freshly drawn 

 blood with a glass rpd or a bundle of twigs ; upon which the fibrin 

 coagulates, and adheres to the twigs in the form of slender threads 

 and flakes. The fibrin, thus coagulated, is at first colored red by 

 the haematine of the blood-globules entangled in it ; but it may be 

 washed colorless by a few hours' soaking in running water. The 

 fibrin then presents itself 



under the form of nearly 

 white threads and flakes, 

 having a semi-solid consist- 

 ency, and a considerable de- 

 gree of elasticity. 



The coagulation of fibrin 

 takes place in a peculiar 

 manner. It does not solidify 

 in a perfectly homogeneous 

 mass; but if examined by the 

 microscope in thin layers it 

 is seen to have a fibroid or 

 filamentous texture. In this 

 condition it is said to be 

 "fibrillated. v (Fig.62.) The 



Fig. 62. 



showing its fibrillated con- 



dition. 



