THE CIRCULATORY SYSTEM 



135 



Flat view 



^SBasssS) Side view 



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THE PROPERTIES OF THE BLOOD AND LYMPH 



The blood is a red fluid, alkaline in reaction, with a peculiar 

 odor thought to be due to a volatile fatty acid. The specific 

 gravity of horse blood is 1060. When drawn from an artery the 

 blood has a bright scarlet color. Venous blood is dark red in 

 color, but on standing in the air readily be- 

 comes scarlet, due to the absorption of 

 oxygen. The total amount of blood is equal 

 to about one-fourteenth of the body weight. 



Blood contains about 750 parts of water 

 to 250 parts of" solids. The proportion of 

 water and solids is but little increased by 

 drinking and only slightly decreased by 

 thirst. The balance, as has been explained, 

 is maintained by the kidneys. The principle 

 solids consist of sodium chlorid, calcium, 

 magnesium, and potassium salts, hemoglobin, 

 various proteins, lecithin, sugar, urea, phos- 

 phoric acid, uric acid, creatin, creatinin, and 

 traces of cholesterin and fat. 



Blood-corpuscles are the formed elements 

 of blood. They are of two kinds, viz., white 

 and red, and are present in the proportion of 

 about 1 to 500 respectively. The while 

 corpuscles, or leukocytes, are colorless 

 nucleated cells. Several kinds are.recognized 

 and the proportion existing between them is 

 a valuable guide in diagnosing diseases. 

 Some originate in the red marrow of bones, 

 others in the lymph glands. By virtue of 

 their ameboid movement they have the 

 ability to pass through intact vessel walls 

 without causing harm. They are active 

 agents in protecting the body against disease- 

 producing microorganisms through their 

 phenomena of engulfing and ingesting foreign particles with 

 which they come in contact. On account of possessing these 

 powers, they are sometimes known as phagocytes or eating 

 cells. The red corpuscles, or erythrocytes, are biconcave disks, 

 without nuclei, measuring K500 inch in diameter in the horse 



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Rouleau 



Fig. 44.— Red blood- 

 corpuscles. Several 

 are shown in different 

 positions. The bicon- 

 cave shape when 

 viewed from the edge 

 is clearly evident. 

 (Hill's Histology.) 



