212 THE SEASON WHY. 



' As for man his days are as grass ; as a flower of the field so he flourisheth." 

 PSALM cm. 



The capillary extremities of the arteries, unite with the capillary 

 extremities of the veins, and the blood passes from the one set of 

 vessels into the other. As the arteries become smaller from the 

 point where they receive the blood, so the veins grow larger ; the 

 venous capillaries, pour their contents into small vessels, and these 

 again into larger ones, until the great venous trunks are reached, 

 and the blood is passed again into the heart as at first described. 

 (Fig. 50.) 



896. Why do we see Hue marks upon our arms and 

 hands ? 



Because large veins lie underneath the skin, through which the 

 blood of the fingers and hand is conveyed back to the heart. 



897. WJiy are the veins more perceptible than the 

 arteries ? 



Because the arteries are buried deeper in the flesh, for 

 protection. It would be more dangerous to life to sever by 

 accident an artery than a vein. A person might bleed longer 

 from a vein than from an artery, without endangering life ; because 

 the arteries supply the life sustaining blood. The Almighty, 

 therefore, has buried the arteries for safety. 



898. Why when we prick the flesh with a needle does it 

 bleed? 



Because the capillary arteries and veins are so fine, and are so 

 thickly distributed all over the body, that not even the point of a 

 needle can enter the flesh without penetrating the coats of several 

 of these small vessels. 



899. What occurrs during the circulation of the blood ? 



Not only do the various parts to which the boats are sent take 

 from them whatever they require, but the boats collect all those 

 matters for which those parts have no further use. The bones, 

 the nerves, the muscles, &c., all renew themselves as the 

 boats pass along; and all give something to. the boats to 

 bring back. One of the chief exchanges is that of oxygen for 



