THE HUMAN FRAME. 7 1 



simple. The first stage of its progress is occupied in passing from the lungs 

 to the left cavity of the heart; the left cavity of the heart then contracts 

 and forces it along the arteries (the vessels that pulsate), and by them 

 it is conveyed to every part of the body to bestow nourishment upon the 

 different parts. All the demands of the system in the way of nutrition 

 being supplied, the blood returns through the veins to the right cavity 

 of the heart, and from thence to the lungs to be purified. When purified 

 in the lungs it pursues the same route anew. By the preceding 

 description it will be seen, that the colour of the blood becomes changed 

 during its passage through the lungs, from a deep purple to a bright red. 

 In the arteries it is always of the vermillion colour, and in the veins it 

 is uniformly blackish or deep purple. One vessel excepted, professional 

 men never let blood from an artery, for if once cut, an artery of any 

 considerable size is not likely to stop bleeding unless it be tied at the 

 point with a thread. The exception to this rule is a small artery which 

 may be felt, and in many persons seen, pulsating on the temples. This 

 vessel is sometimes opened in apoplexy, and in very dangerous cases of 

 disease of the head. If an artery is punctured, the blood comes out in 

 jets at intervals, but from a vein it flows in a continuous stream. 



TUB PULSE 



In the new born infant is from 130 to 140 beats per minute, but 

 decreases in frequency as life advances ; so that in a middle-aged adult in 

 perfect health, it is from 72 to 75. In the decline of life it is slower than 

 this, and falls to about 60. It is obvious, that if a medical practitioner 

 should be ignorant of this, he would commit the most awful blunders, 

 and might be liable to imagine a boy of ten years of age to be labouring 

 under some disease, because his pulse had not the slow sobriety of his 

 grandfather's. A more likely error is to mistake the influence of some 

 temporary cause for the presence of some permanent disease. Thus, in a 

 nervous patient, the doctor's knock at the door will quicken the pulse 

 between 15 or 20 beats a minute. Celsus named this eighteen centuries 

 ago, (and its truth is acknowledged now), and recommends the careful 

 physician not to be in a hurry to feel the pulse of his patient. But if 

 these sources of error are avoided, yet the quickness of the pulse will 

 afford the most important information. If in a person, for example, 

 whose pulse is usually 72, the beats rise to 98, some alarming disease is 



