The Pedestrian's Record

106 the pedestrian's record. sometimes involves the brain also in diseases. Inject pus (bad matter) into the blood, and abscesses will ultimately make their appearance in various parts of the body. Administer to an ox through the medium of his mouth, or inject into his veins, white hellebore, and the symptoms ofvomiting will be induced. To a person unacquainted with physiological inquiry the above may appear strange, but not so when we con­ sider the beautiful provision Nature has made to purify the blood. First, by supplying a chamber (the lungs), in which to receive a purifying gas, wherein chemical decomposition of a very important nature may be carried on ; these important functions being that a certain or fixed amount of oxygen shall becon-^ veyed during each inspiration to the lungs, in order to keep up animal heat, decarbonize the blood, and thereby sustain life, and that carbonic acid during ex­ piration shall be expelled from the lungs. It will now be readily understood that if oxygen deficient in amount be inspired, an unnatural state of things will be produced. And further, that if carbonic acid gas sufficient in amount be not expired, a certain amount of poisonous gas must be thrown back on the system, and, as a consequence, the blood will become too strongly impregnated with carbon, and the nervous system will suffer. But, should disease occur to the lungs—should certain tubes become blocked up, or should the blood-vessels therein be implicated in disease—the due amount of oxygen, owing in the latter case to mechanical obstruction, cannot be in-