THE CIRCULATION 



at a resurrection. The body seems to move, little by little 

 strength returns, and finally the animal rises. The life has 

 returned because the vital combustion, not totally extin- 

 guished, was resumed when the blood reentered the vessels. 



134. It is found that the heart stops beating, or beats 

 very faintly, just before a person faints. What does this 

 show to be constantly needed that the mind may work ? 



Give a proof that blood is present almost everywhere in 

 the body. 



Explain why blushing is a proof of this fact ? What two 

 kinds of tissue are destitute of blood vessels (Chapter II)? 



135. The Problems, the answers to which we are to 

 study in this chapter, are : the composition of blood, the 

 reasons for this composition, and how the blood is dis- 

 tributed to the different cells and tissues. 



136. Composition of the Blood. When seen under the 

 microscope blood no longer appears of a uniform red 

 color. It is found to con- 

 sist of a clear, colorless 



liquid called plasma, in 

 which floats a multitude 

 of small bodies called cor- 

 puscles. The corpuscles 

 themselves are seen to be 

 of two kinds. By far the 

 greater number are round, 

 yellow, and flattened, but 

 a few, perhaps one in four 

 hundred, are round, white, 

 and globular, and larger than the yellow ones (Fig. 80). 

 The yellow ones are called the red corpuscles, because the 

 light shining through a great number of them gives the 

 blood a red color. 



137. Reasons for the Composition of the Blood. That 

 the blood may flow readily through every little tube, it 



FIG. 80. 



B, red corpuscles seen from the side ; D, red cor- 

 puscles, seen on edge, are run together in rows; 

 G, F, colorless corpuscles. 



