45 



BLOOD. 



The Blood is a nutritive fluid containing all the elements necessary for 

 the repair of the tissues ; it also contains principles of waste absorbed from 

 the tissues, which are conveyed to the various excretory organs and by them 

 eliminated from the body. 



The total amount of blood in the body is estimated to be about one- eighth 

 of the body weight ; from 1 6 to 18 pounds in an individual of average physi- 

 cal development. The quantity varies during the 24 hours; the maximum 

 being reached in the afternoon, the minimum in the early morning hours. 



Blood is a heterogeneous, opaque red fluid, having an alkaline reaction, 

 a saline taste, and a specific gravity of 1.055. 



The opacity is due to the refrac.tion of the rays of light by the elements 

 of which the blood is composed. The color varies in hue, from a bright 

 scarlet in the arteries to a deep purple in the veins, due to the presence of 

 a coloring matter, hemoglobin, in different degrees of oxidation. 



The alkalinity is constant, and depends upon the presence of the alka- 

 line sodium phosphate, Na 2 HPO 4 . 



The saline taste is due to the amount of sodium chloride present. 



The specific gravity ranges within the limits of health, from 1.045 to 1.075. 



The odor of the blood is characteristic, and varies with the animal from 

 which it is drawn, due to the presence of caproic acid. 



The temperature of the blood ranges from 98 Fahr. at the surface to 

 107 Fahr. in the hepatic vein; it loses heat by radiation and evaporation 

 as it approaches the extremities, and as it passes through the lungs. 



Blood consists of two portions : 



1. The Liquor Sanguinis or Plasma, a transparent, colorless fluid, in 

 which are floating 



2. Red and white corpusjes; these constituting by weight less than one- 

 half, 40 per cent., of the entire amount of blood. 



COMPOSITION OF PLASMA. 



DALTON. 



Water, 902.00 



Albumin, 53.00 



Paraglobulin, 22.00 



Fibrinogen, 3.00 



Fatty matters, 2.50 



Crystallizable nitrogenous matters, 4.00 



Other organic matter, 5 <o 



Mineral salts, 8.50 



1000.00 



