DELUSIONS 87 



(2) that there was gravel in the head. The examination of the brain of 

 the first of these cases revealed lesions in the optic thalamus. When we 

 recall the fact that the thalamus is a subsidiary, although very impor- 

 tant, sensory ganglion which receives the nervous impulses correspond- 

 ing with the sensations of touch, pressure, temperature and pain, be- 

 fore these impulses are passed onwards to the cerebral cortex, and that 

 in the non-insane lesions of this ganglionic mass result in anaesthesias, 

 it is not difficult to understand that this particular cerebral lesion may 

 have a very definite relation to the belief that the insides are gone. 

 A similar correlation has also been recorded by Southard in the case in 

 which the belief that " the insides were gone " was associated with a 

 lesion in the cerebral postcentral gyri (sensory center). 



It will be noted that these cases in which somatopsychic delusions 

 are associated with variations in the sensations from the bodily periphery 

 resemble those conditions which are grouped under the general head- 

 ing of illusions. In certain cases those beliefs which are apparently 

 delusions might very readily be considered to be paresthesias (illu- 

 sions), but there is one particular in which they sometimes differ, 

 viz., the delusions can not be correlated with definite changes in parts 

 of the body until after death. This is especially true for those cases 

 in which the delusion or false belief has been associated with a lesion of 

 part of the cerebrum. If we should carefully and consistently omit 

 from the class of delusions all those conditions in which there are con- 

 comitant physical abnormalities which might result in sensory abnor- 

 malities, we should probably classify the above cases of Southard with 

 illusions or hallucinations. Since, however, many of the physical 

 pathological conditions can not be determined until after death, we 

 should need to withhold any particular designation until after that 

 event, and an accurate designation could not then be made unless an 

 autopsy were performed. It would therefore not be possible to dis- 

 tinguish between delusions and illusions and hallucinations. Obvi- 

 ously the matter must be settled in a more practical manner and it 

 appears best to designate the more definite interpretative elaborations 

 as delusions regardless of their source. Thus, internal ear diseases may 

 result in sensations which give rise to the reports that "there is a 

 buzzing in my ears," or " people are talking about me," or " there are 

 bees in my head." Since it is not possible to determine in every case 

 the definite relation of an idea to a particular stimulation the interpre- 

 tative additions of the last two forms of reaction give warrant for the 

 designation of delusion. The indefiniteness of the "buzzing in my 

 ears" is similar to the well-known paresthesias of tingling and formi- 

 cation, and may be classed with these, even though the morbid process 

 leading to the abnormal sensations be unknown. The interpretative 

 elaboration may in these cases be the only criterion differentiating the 

 delusion from an hallucination or an illusion. 



