^72 ANNALS NEW YORK ACADEMY OF SCIENCES 



of external stimuli, or, in short, a perception without an object. Illu- 

 sions were defined as the false interpretation of external objects ; L e., an 

 illusion is the falsification of a real percept. The speaker admitted that 

 cases might occur in which ideas originating wholly in the cortical center 

 might become so vivid as to be taken for sensations that had arisen by 

 stimulation of the sense organs — but he believed that these cases were 

 much less common than is generally supposed. 



It was shown that the various authorities differed greatly as to the 

 frequency of hallucinations and illusions in the various forms of insanity. 

 Each of the various psychoses were considered. In dementia paralytica, 

 for example, the elder Falret absolutely denied their existence. Kraft- 

 Ebbing says they are so rare that where they are found one should suspect 

 a false diagnosis. Yet Jung, Saury, and Mickle concur in saying that 

 they occur in over one half of all cases. 



The part that the various senses play in the fallacious perceptions of 

 the insane was then considered. Though this depends somewhat on the 

 psychosis, both hallucinations and illusions of hearing are much more 

 frequent than those of any of the other senses or even combination of the 

 senses. In one form of mania sight hallucinations were found to be 

 greater in number than auditory hallucinations. Hallucinations of taste 

 are very rare. The speaker considered it doubtful if the so-called gusta- 

 tory hallucinations occasionally seen in dementia paralytica were true 

 hallucinations. His experience led him to believe that they were rather 

 the result of delusions, in that when a delusion was being "described^' 

 by a patient he naturally made his ideas and feelings "fit" accordingly. 

 Of the 361 cases of dementia prcecox and maniac depressive insanity 

 tested, only 4 were found having fallacious perceptions of taste, either 

 alone or in combination. 



In some cases, the patient informs the physician of his own accord 

 regarding his hallucinations and illusions; in others, the information 

 sought for must be obtained by some roundabout method. Care must be 

 taken that reported hallucinations are not really illusions; for example, 

 when in a noisy ward a patient hears herself being called a witch, it is 

 difficult to decide whether she is experiencing an hallucination or an 

 illusion. When, however, the morbid perception occurs in absolute silence 

 we may feel reasonably certain that the patient experiences an hallucina- 

 tion. It was shown that in those cases in which the patient is suspected 

 of endeavoring to conceal the fact that he experiences hallucinations, con- 

 siderable work may be necessary before their presence or absence can be 

 definitely determined. Careful observation of the patient when he is 

 unaware that he is being watched is, of course, necessary in many cases. 



