HALLUCINATOKT MANIFESTATIONS. 
63 
sense to the sensorium is so perverted that modifications of 
external impressions are both induced and sustained. The 
delicate muscular mechanism by which the two great organs of 
the senses, the eye and the ear, have their various parts cor- 
rectly adapted, are under refined nervous control, and easily 
loose their adaptations when the nervous control is either de- 
fective or changed from its natural use. The nervous atmosphere 
through which impressions vibrate from the receiving surface 
to the receiving centres is susceptible of change, and thus 
under various circumstances there is an easy step to perverted 
appreciation of external things. We have many known agents 
which exert their power by thus interfering with the healthy 
relations that should subsist between the organs of sense, the 
conducting way, and the mental centres to which all impres- 
sions are finally delivered. Alcohol taken in excess leads to 
such disturbance of balance of action, and therewith to false 
impressions of external objects — phantoms not made by the 
imagination, but constructed out of perverted sensual action. 
Opium, haschish, and some vapours and gases made to enter 
the body, induce the same perversions. So that objects that are 
really before the observer to the perverted sight ajopear far 
distant, or larger or smaller than they are. Slight sounds are 
exaggerated into tempestuous noises, and sensations of smell, 
taste, and touch, are either exalted into undue activity or lost 
altogether. 
In connection with this subject I may observe that the ten- 
dency of recent physiological research is to the effect that in 
certain conditions of the body there are produced, within the body 
itself, some organic products which in the most potent manner 
affect the organs of the senses, and interfere, with their function. 
In a recent investigation on the action of organic compounds 
of the sulphur series, I found that the most marked changes in 
the reception of impressions could be induced by certain of 
these bodies, together with symptoms of hysteria and of muscu- 
lar debility singularly analogous to those states of the body in 
which debility of the motor organs is attended with what is 
called excessive nervous susceptibility and excitability. In 
certain diseased states these same organic products exhale from 
the body, or pass off by the secretions, as products derived from 
organic chemical changes progressing within the organism. 
It would be an easy task to fill page upon page with illustra- 
tions of translations of external objects into mysterious mani- 
festations under the mere influence of perverted functions of 
the senses and their dependent parts ; but I must forbear, and 
content myself with one remark in reference to these pheno- 
mena. The remark is this : that the man, under any of the 
influences cited, is never supposed to be anything less than de- 
