Human Physiology. 



diseases can be communicated by inoculation, and apparently 

 by contagion, or by the inhalation of expectorated and dried 

 tuberculous matter. 



Local diseases, enumerated in the five orders of Class III., 

 include many of the most severe and fatal. Men die suddenly 

 of apoplexy, or pressure upon the brain from the effusion of 

 blood or serum ; they perish slowly of paralysis, or a failure of 

 nervous action; and epilepsy, mania, and other disorders of 

 the brain and nerves have many unhappy victims. The heart, 

 arteries, and veins are weakened in action by the loss of ner- 

 vous energy, or of the tone of their own tissues. The heart is 

 a collection of muscles, and these may become weak or fall 

 into a fatty degeneration. The valves of the heart may be 

 affected by disease, and unable to perform their functions. 

 Weakened veins may fail to carry the blood back to the heart. 

 Great arteries may distend and burst. The mucous membrane 

 of the throat and bronchial tubes, the substance of the lungs and 

 its lining membrane, the pleura, are liable to inflammation, 

 congestion, and change or destruction of substance. Spas- 

 modic constrictions produce distressing difficulty of breathing. 

 The stomach and bowels are subject to inflammations and 

 congestions, chiefly of the mucous membrane and its glands, 

 with excessive and morbid action, as in diarrhoea and dysentery. 

 The liver may be inflamed come into a state of local fever 

 and congestion, or become torpid. The kidneys, organs of 

 the most vital importance, are liable to disordered action and 

 violent and painful disease, or gradual decay, as are also the 

 bladder, testes, ovaries, and womb. Disease attacks also 

 bones, muscles, cartilages, and the skin. The eye, the ear, 

 the teeth every organ of the body is liable to irritation, weak- 

 ness, inflammation, and painful diseases. 



But of the real nature of all these diseases, or forms of dis- 

 ease, we know very little. We can but describe symptoms, or 

 the observable phenomena the quickened pulse, the height- 



