HjEMORIUTAGIES. 205 



casioned, if the system becomes preternaturally plethoric ; but 

 hoemorrhagy has always a tendency to increase the plethoric 

 state of the system, and, consequently, to occasion its own re- 

 turn. 



DCCXLVIII. To show that haemorrhagy does contribute 

 to produce or increase the plethoric state of the system, it is only 

 necessary to observe, that the quantity of serous fluids being 

 given, the state of the excretions depends upon a certain bal- 

 ance between the force of the larger arteries propelling the 

 blood, and the resistance of the excretories : but the force of the 

 arteries depends upon their fulness and distention, chiefly given 

 td them by the quantity of red globules and gluten, which are, 

 for the greatest part, confined to the red arteries ; and, therefore, 

 the spoliation made by an hoemorrhagy, being chiefly of red 

 globules and gluten, the effusion of blood must leave the red 

 arteries more empty and weak. In consequence of the weaker 

 action of the red arteries, the excretions are in proportion dimin- 

 ished ; and, therefore, the ingesta continuing the same, more 

 fluids will be accumulated in the larger vessels. It is by this 

 means that the loss of blood by hsemorrhagies, whether artificial 

 or spontaneous, if within certain bounds, is commonly so soon 

 recovered ; but as the diminution of the excretions, from a less 

 quantity of fluid being impelled into the excretories, gives occa- 

 sions to these vessels to fall into a contracted state ; so, if this 

 shall continue long, these vessels will become more rigid, and 

 will not yield to the same impelling force as before. Although 

 the arteries, therefore, by new blood collected in them, shall 

 have recovered their former fulness, tension, and force, yet this 

 force will not be in balance with the resistance of the more rigid 

 excretories, so as to restore the former state of excretion ; and 

 consequently, a farther accumulation will take place in the ar- 

 teries, and an increase of their plethoric state be thereby in- 

 duced. In this manner, we perceive more clearly, that haemorr- 

 hagy, as producing a more plethoric state of the system, has a 

 tendency to occasion its own recurrence with greater violence ; 

 and, as the renewal and further accumulation of blood require a 

 determinate time, so, in the several repetitions of hoemorrhagy, 

 that time will be nearly the same ; and therefore the returns of 



