VESANI^E. 519 



specific gravity. Whether these different states have been ob- 

 served to be uniformly the same over the whole of the brain, 

 I cannot certainly learn ; and I suspect the dissectors have not 

 always accurately inquired into this circumstance ; but, in se- 

 veral instances, it appears that these states had been different in 

 different parts of the brain ; and instances of this inequality will 

 afford a confirmation of our general doctrine. 



The accurate Morgagni has observed, that in maniacal per- 

 sons the medullary portion of the brain is unusually dry, hard, 

 and firm : And this he had so frequently observed, that he was 

 disposed to consider it as generally the case. But in most of 

 the particular instances which he has given, it appears, that, for 

 the most part, while the cerebrum was of an unusually hard and 

 firm consistence, the cerebellum was of its usual softness ; and 

 in many of the cases it was unusually soft and flaccid. In some 

 other cases, Morgagni observes, that while a part of the cere- 

 brum was harder and firmer than ordinary, other parts of it were 

 preternaturally soft. 



MDLII. These observations tend to confirm our general 

 doctrine ; and there are others which I think will apply to the 

 same purpose. 



Upon the dissection of the bodies of persons who had labour- 

 ed under insanity, various organic affections have been discover- 

 ed in particular parts of the brain ; and it is sufficiently proba- 

 ble, that such organic affections might have produced a differ- 

 ent degree of excitement in the free and affected parts, and must 

 have interrupted in some measure the free communication be- 

 tween the several parts of the brain, and in either way have oc- 

 casioned insanity. 



There have occurred so many instances of this kind, that I 

 believe physicians are generally disposed to suspect organic le- 

 sions of the brain to exist in almost every case of insanity. 



MDLIII. This, however, is probably a mistake; for we 

 know that there have been many instances of insanity frohi 

 which the persons have entirely recovered ; and it is difficult to 

 suppose that any organic lesions of the brain had in such case 

 taken place. Such transitory cases, indeed, render it probable, 

 that a state of excitement, changeable by various causes, had 

 been the cause of such instances of insanity. 



