168 PHYSIOLOGY. 



nearly neutral; the concentration of the hydroxyl ions is nearly the 

 same as in distilled water. 



Freudeberg states that an ounce of dilute lactic acid in one day 

 reduced the alkalinity of the blood one-fourth, whilst two drachms 

 of tartaric acid diminished it one-sixth. 



Blood maintains its consistency in composition by the excretion 

 of the kidneys and exudation into the lymph spaces of tissues. 



Life is incompatible with an acid blood, for an injection of an 

 acid by the vein quickly causes coma and death, as in the acidosis 

 of diabetes. Venous blood is less alkaline than arterial blood. Its 

 alkalinity is chiefly due to the presence of disodic phosphate and 

 bicarbonate of soda. 



Taste. Blood possesses a distinctly salty taste. 



Specific Gravity. The specific gravity of normal, healthy blood 

 varies within certain limits: for men, about 1.057. to 1.066; for 

 women, 1.054 to 1.061. Its density is influenced by various factors 

 and conditions. If fluids be used sparingly and a dry diet eaten, 

 the density is increased. It is also increased by exercise and pro- 

 fuse sweating. It falls when fluid is injected into the vessels, but 

 for a short time only. 



Temperature. The temperature of the blood varies between 

 97.7 and 100 F. The cutaneous blood-supply is slightly lower in 

 temperature, while the warmest blood is that in the hepatic vein; 

 the coldest in the tip of the nose. 



Odor. Fresh blood imparts a decided odor, peculiar to the 

 animal from which it is drawn. The odor of blood is due to volatile 

 fatty acids held in solution. The effect becomes more striking upon 

 the addition of concentrated sulphuric acid to the blood. 



Viscosity. The viscosity of the blood considerably exceeds that 

 of the plasma, or that of the serum, and is dependent upon the num- 

 ber of suspended blood corpuscles. 



Burton-Opitz made blood laky by repeated freezings, and found 

 the viscosity diminished. The viscosity is increased by the increase 

 of carbonic acid in the blood ; hence venous blood has more viscosity, 

 according to Burton-Opitz, than arterial. Burton-Opitz has shown 

 that hunger reduces viscosity and meat diet raises it to a great 

 height, whilst carbohydrates and fat diet give average values to it. 

 Hiirthle has found in animals and Hirsh and Beck in man that it 

 is inversely related to the coagulation time; hence the less the 

 viscosity the greater the time in coagulation. 



High altitudes increase the viscosity of the blood. The specific 



