188 THE POPULAR SCIENCE MONTHLY. 



When the degeneration of the right heart has progressed to a cer- 

 tain extent, incompetency of the tricuspid valve follows either with or 

 without the aid of an exciting cause. Hence it is easy to understand 

 why dilatation of the right heart and tricuspid incompetency are often 

 found to exist apart from any previous history of cardiac disease. 



The third great vital function which influences the degenerative 

 tendency of the heart is that of the circulation of the blood. To pre- 

 serve the health of the tissues, the blood mtist not only be pure and 

 rich in the materials of growth, but it must flow with a certain speed 

 through all the blood-vessels. If the speed with which the blood 

 moves is on the side of either plus or minus of the standard of health, 

 disease will shortly arise. If it is on the side of plus, active disease 

 of the heart, where that organ is the one to suffer, will follow. If on 

 the side of minus, tissue degeneration will ensue. Active disease will 

 be the consequence before middle age ; degeneration after that period. 



These facts teach that all violent and long-continued efforts of the 

 body should be avoided. They hurry the heart's action to an inordi- 

 nate degree, they cause it to throw the blood with great force into the 

 extreme vessels, and, as there is almost always one organ of the body 

 weaker than the others, the vessels of this organ become distended, 

 and, remaining distended, the organ itself becomes diseased. Run- 

 ning, rowing, lifting, jumping, wrestling, severe horse-exercise, cricket, 

 football, are fruitful causes of heart-disease. Those which require the 

 breath to be suspended during their accomplishment are more fruitful 

 causes in this respect than those which require no such suspension of 

 the breathing. Rowing, lifting heavy weights, wrestling, and jump- 

 ing, do this ; and, of these, rowing is the most powerful for evil. At 

 every effort made with the hands and feet, the muscles are strained to 

 their utmost ; the chest is violently fixed ; no air is admitted into the 

 lungs ; blood is thrown by the goaded heart with great force into the 

 pulmonary vessels ; they become distended ; they at length cannot 

 find space for more blood ; the onward current is now driven back 

 upon the right heart ; its cavities and the blood-vessels of its walls 

 become in like manner distended ; the foundation of disease is laid. 

 Hypertrophy, haemoptysis, inflammatory affections of the heart and 

 lungs, are the consequences in the young ; valvular incompetency, rup- 

 ture of the valves or of the muscular fibres of the heart, pulmonary 

 apoplexy, and cerebral haemorrhage, are too frequently the immediate 

 consequences in those of more mature years. 



If the flow of blood is minus the standard of health, the heart's 

 walls are imperfectly nourished, by reason of a deficient supply of food 

 within a given time ; the blood itself, receiving less aeration, is, in con- 

 sequence, more impure ; degeneration of the heart's walls is thus in- 

 duced, if it does not already exist hastened, if it is present. 



I propose now to consider the influence of an increasng quantity of 



