Human Frame. 24 jL 



and vascular system, full of nutritious and 

 .nicies, fluid, and able to pene- 

 trate into the minutest parts of the ani- 

 mal ; impeilfd by the heart, and convey- 

 ed by the arteries, it washes every part, 

 builds up what was broken down, and 

 sweeps away the old useless materials. 

 Hence we see the necessity or advan- 

 tage of the heart and arterial system. - 

 What more than enough there was of the 

 blood to repair the present damages of 

 the machine, must not be lost, but should 

 be returned again to the heart ; and for 

 this purpose the veins are actually provid- 

 ed. These requisites in the animal, ex- 

 plain a priori, the circulation of the 

 blood. The old materials, which are be- 

 come useless, and are swept off by the 

 current of the blood, must be separated 

 and thrown out of the system. Therefore 

 the glands, the organs of secretion, are 

 given for straining whatever is redun- 

 dant, vapid, or noxious, from the mass of 

 blood ; and, when strained, they are 

 thrown out by entunctories, called organs 

 of excretion. But now, as the machine 

 must be constantly wearing, the opera- 

 tions must be carried on without inter- 



