COMATA. 339 



exhalents, as in other cases of hydropic diathesis prevailing in 

 the body ; and it is not unusual for a general dropsy to end in 

 apoplexy. The second is an over-proportion of watery parts in 

 the mass of blood, which is therefore ready to run off* by the 

 exhalents, as in the case of an Ischuria renalis ; which, when it 

 proves incurable, very commonly terminates in apoplexy. 



" The cranium is very accurately fitted to its contents : and 

 any turgescence must certainly be limited by it : if the blood- 

 vessels therefore are upon any occasion preternaturally distend- 

 ed, they must occupy the place allotted to them and to the 

 medullary substance. I would therefore not consider the state 

 as a compression on the origin of the nerves, but rather as a 

 general dilatation of the whole cortical substance, and of the 

 vessels interposed in it, operating by a compression on the whole 

 medullary substance." 



M CXI 1 1. We have now mentioned the several causes of 

 apoplexy depending upon compression ; and from the whole it 

 will appear that the most frequent of all these causes is a 

 plethoric state, or an accumulation and congestion of blood in 

 the venous vessels of the head, operating, according to its degree, 

 in producing over-distention or effusion. The frequent opera- 

 tion of such a cause will especially appear from a consideration 

 of the predisponent circumstances (MXCV.), and from the 

 antecedent symptoms (MXCVI.). 



MX IV. From the view I have now given of the causes of 

 apoplexy arising from compression, it will readily appear that 

 there is a foundation for the common distinction of this disease 

 into the two kinds of Sanguine and Serous. But this distinc- 

 tion cannot be very usefully applied in practice, as both kinds 

 may often depend on the same cause, that is, a venous plethora, 

 and therefore requiring very nearly the same method of cure. 

 The only distinction that can be properly made of apoplexies 

 from compression, is perhaps the distinction of serous apoplexy, 

 into that depending on the plethora mentioned MCXIIL, and 

 that depending on hydropic diathesis, or an over-proportion of 

 water in the blood (MCXII.) ; the former causes giving a 

 proper idiopathic, the latter only a symptomatic disease. 



MCXV. Besides the causes now mentioned, occasioning apo- 

 plexy by compression, I allege there are other causes producing 



Y2 



