208 PRACTICE OF PHYSIC. 



ceed to operate till every part of the system, in respect of density 

 and resistance, shall have been brought to be in balance with 

 every other, and till the whole be in balance with the force of 

 the heart, so that there can be no further growth in any partic- 

 ular part, unless some preternatural circumstance shall happen 

 to arise. 



DCCLV. In this process of the growth of the body, as it 

 seems in general to depend upon a certain balance between 

 the force of the heart, or distending power, and the resistance 

 of the solids ; so it will appear, that, while the solids remain 

 very lax and yielding, some occasional increase of the distending 

 power may arise, without producing any very perceptible dis- 

 order in the system. But it will also appear, that, in propor- 

 tion as the distending power and resistance of the solids come 

 to be more nearly in exact balance with one another, so any in- 

 crease of the distending power will more readily produce a rup- 

 ture of vessels, which do not easily yield to extension. 



DCCLVI. From all this, it must follow, that the effects of 

 any unusually plethoric state of the system, will be different 

 according as this shall occur at different periods of the growth 

 of the body. Accordingly, it is evident, that if the plethoric 

 state arises while the head is yet growing, and while the deter- 

 mination of the blood is still more to the head than to the other 

 parts, the increased quantity of the blood will be especially 

 determined to the head ; and as there also, at the same time, 

 the balance between the distending and extending powers is 

 most nearly adjusted, so the determination of the blood will 

 most readily produce in that part a rupture of the vessels, or 

 an haemorrhagy. Hence it is, that hsemorrhagies of the nose 

 so frequently happen in young persons ; and in these more 

 readily as they approach nearer to their acme, or full growth ; 

 or it may be said, perhaps more properly, as they approach 

 nearer to the age of puberty, when perhaps in both sexes, but 

 especially in the female, a new determination arises in the 

 system. 



DCCLV II. The determination of a greater quantity of 

 blood to the vessels of the head, might be supposed to occasion 

 a rupture of vessels in other parts of the head, as well as in the 

 nose : but such a rupture does not commonly happen ; because 



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