518 PRACTICE OF PHYSIC. 



or not at all changed. I must therefore say again, that how diffi- 

 cult soever it may be to explain the mechanical or physical con- 

 dition of the brain in such cases, the facts are sufficient to show 

 that there is such an inequality as may disturb our intellectual 

 operations. 



MDL. I have thus endeavoured to explain the general cause 

 of Delirium : which is of two kinds ; according as it is with or 

 without pyrexia. Of the first I take no further notice here, 

 having explained it as well as I could above, in XLV. 



I proceed now to consider that delirium which properly be- 

 longs to the class of Vesanise, and which I shall treat of under 

 the general title of Insanity. 



" I am still doubtful whether I am sufficiently exact in my de- 

 finition of Insania (See Synopsis NosoL Note to gen. XLV.). 

 I have had too strictly in view the Error mentis judicantis. 

 Gaubius is more complete in his definition of delirium, as affect- 

 ing all the faculties of the mind, perception, judgment, and will 

 (Patholog. 732.). I omitted false perception and erroneous 

 will, because I had excluded both the Hallucinationes and Mo- 

 rositates from the order of Vesanise. But I had excluded them 

 in so far as they depend on a fault or disease of the external 

 organs ; and I now perceive, that I should have retained them 

 more distinctly in so far as they depend on the brain itself. I 

 truly do this, but not explicitly enough ; and, taking Gaubius 1 

 definition of delirium, I might have defined Insania, as applica- 

 ble to our present case, delirium sinefebre" 



MDLI. In entering upon this subject, it immediately oc- 

 curs, that in many instances of insanity, we find, upon dissec- 

 tion after death, that peculiar circumstances had taken place in 

 the general condition of the brain. In many cases, it has been 

 found of a drier, harder, and firmer consistence, than what it is 

 usually of in persons who had not been affected with that dis- 

 ease. In other cases, it has been found in a more humid, soft, 

 and flaccid state ; and in the observations of the late Mr. Mec- 

 kel,* it has been found considerably changed in its density or 



* Memoires de Berlin pour 1'annee 1764. It appeared in many instances of insane per- 

 sons, that the medullary substance of the cerebrum was drier, and of a less specific grav- 

 ity, than in persons who had been always of a sound judgment. 



