102 



THE CIRCULATION: 



Qedle. The total quantity of blood in the body is esti- 

 mated at about one-eighth of its weight, or eighteen 

 pounds. 



3. The color of the blood, in man and the higher ani- 

 mals, as is well known, is red ; but it varies from a bright 

 scarlet to a dark purple, according to the part whence it is 

 taken. " Blood is thicker than water," as the adage truly 

 states, and has a glutinous quality. It has a faint odor, 

 resembling that peculiar to the animal from which it is 

 taken. 



4. When examined under the microscope, the blood no 

 longer appears a simple fluid, and its color is no longer red. 

 It is then seen to be made up of two distinct parts: first, 

 a clear, colorless fluid, called the plasma ; and secondly, 

 of a multitude of minute solid bodies, or corpuscles, 

 that float in the watery plasma. The plasma, or nutritive 

 liquid, is composed of water richly charged with materials 

 derived from the food, viz., ' albumen, which gives it 

 smoothness and swift motion; fibrin; certain fats; traces 

 of sugar; and various salts. 



5. The Blood Corpus- 

 cles. In man, these remark- 

 able "little bodies," as the 

 word corpuscles signifies, are 

 of a yellow color, but by their 

 vast numbers impart a red 

 hue to the blood. They are 

 very small, having a diameter 

 of about -j^Vo f an inch, and 

 being one-fourth of that frac- 

 tion in thickness; 'so that if 

 3,500 of them were placed in 

 line, side by side, they would only extend one inch; or, if 



FIG. 25. THE BLOOD CORPUSCLES. 



3. Color of blood? Its consistence ? Odor? 



4. What is stated of the blood an viewed under the microscope ? 



5. State what you can of the little bodies called corpuscles. 



