2 THE CANADIAN HOESE 



constituents of the blood ;* but, if we follow it on till it ter- 

 minates in the capillaries, the current becomes much slower,, 

 and we can distinctly observe the corpuscles, (or blood glo- 

 bules,) red and white, moving regularly and smoothly through 

 them, without any tendency to adhere to one another or to 

 the coats of the vessels. If an irritant be applied, or the part 

 pricked with the point of a needle, the vessels at once con- 

 tract or lessen their calibre, but almost immediately dilate to 

 more than their natural size ; the blood now rushes through 

 them with increased rapidity, and the minute vessels which 

 before were invisible are now distended with red blood. If 

 at this stage the stimulus be withdrawn, the vessels resume 

 their usual appearance, and the circulation goes on as before. 

 If, on the other hand, it be continued or increased, the dila- 

 tation increases, the flow of blood becomes slower, the cor- 

 puscles adhere to one another and to the coats of the vessels, 

 the capillaries are distended, exudation through their coats 

 takes place, and the circulation becomes sluggish, and at last 

 stops altogether. The blood still continuing to arrive in 

 increased force and quantity, the surrounding vessels are 

 engorged, and extravasation of liquor-sanguinis, and in 

 some instances blood itself, takes place, and the part becomes 

 red, hot, swollen, and tender, and is now in a state of inflam- 

 mation. The prominent local phenomena observable in a 



• * DlAQBAM OF THE BlOOD. 



Chemical Oomponents. 



Water, ' \ 



Various salts, I 



Liquor 1 ^^^^ matters, ) Serum, 



^ • ■ ' Extractive do., I 



to ) 



sangumis, I Albumen, 



Fibrin, ^ 



Red oorpusolee, I Crassa- | £ 



Colourless corpuscles, | mentum " 



Granules, j ' 



& 



