806 OF THE FUNCTIONS OF THE NERVOUS SYSTEM. 



830. Those more violent forms of Delirium in which there is considerable 

 emotional disturbance, pass by almost imperceptible gradations into the state of 

 Mania, which is usually characterized by the combination of complete derange- 

 ment of the intellectual powers, with passionate excitement upon every point 

 which in the least degree affects the feelings. There is, however, a considerable 

 amount of variety in the phases of Mania, depending upon differences in the 

 relative degree of intellectual and of emotional disturbance. For there may be 

 such a derangement of the former, as gives rise to complete incoherence in the 

 succession of ideas, so that the reasoning power is altogether suspended; and 

 yet there may be at the same time an entire absence of emotional excitement, 

 so that the condition of the mind is closely allied to that of dreaming or of 

 rambling delirium. On the other hand, the intellectual powers may be them- 

 selves but little disturbed, the trains of thought being coherent, and the reason- 

 ing processes correctly performed ; but there may be such a state of general 

 emotional excitability, that nothing is felt as it should be, and the most violent 

 passion may be aroused and sustained by the most trivial incidents, or by the 

 wrong ideas which are formed by the mind as a consequence of their misinter- 

 pretation ( 796). Between these two opposite states, and that in which the 

 disturbance affects at the same time the intellectual and the emotional part of 

 the Mental nature, there is a complete succession of transitional links ; but, 

 under all phases of this condition (these often passing into each other in the 

 same individual), there is one constant element, namely, the deficiency of Voli- 

 tional control over the succession of ideas. This deficiency appears to be a 

 primary element in those forms which essentially consist in Intellectual dis- 

 turbance; whilst in those of which Emotional excitement is the prominent 

 feature, it seems rather to result from the overpowering mastery that is exer- 

 cised over the Will, by the states of uncontrollable passion which succeed each 

 other with little or no interval. It seems probable, however, from the pheno- 

 mena of Intoxication ( 829), that the very same agency which is the cause of 

 the undue Emotional excitability, also tends to produce an absolute diminution 

 in the power of Volitional control. 



881. From the state of Mania, we naturally pass to those more persistent 

 forms of Insanity, in which there is some settled disorder in the action of the 

 Mind. Although this may arise from a perversion of any part of the psychical 

 nature, yet a partial or complete deficiency in the Volitional control over the 

 current of thought, and consequently over the actions which are the expressions 

 of it, seems to be a characteristic feature of every form of Insanity ; and it is 

 this, which, in so far as it exists, ought to be considered as rendering the indi- 

 vidual irresponsible for his actions. It is chiefly (but not solely) in those cases 

 in which the Cerebral power has been weakened by a succession of attacks of 

 Mania, Epilepsy, or some other disorder which consists in a perverted action of 

 the whole organ, that we find the Intellectual powers specially and permanently 

 disordered ; the succession of thought becoming incoherent, and the perception 

 of those relations of ideas on which all reasoning processes depend, being more 

 or less completely obscured. The failure usually shows itself first in the power 

 of Volitional direction, and especially in the faculty of Recollection; in propor- 

 tion as the mind is unable to bring the results of past experience to bear on its 

 present operations, do these lose their connectedness and consistency ; and at 

 last all the ordinary links of association appear to be severed, and (as in the 

 most incoherent kinds of Dreaming) the succession of thoughts cannot be ac- 



selves to hear, seem to result from changes in the Sensorium excited by Cerebral influence ; 

 but in Delirium there is an evidently disordered action of the sensorium itself, of which 

 spectral illusions and other "subjective sensations" are the manifestation. This is par- 

 ticularly obvious in that form of Delirium which is known as delirium tremens. 



