ration in the pulse, and the line registered by the
plethysmograph suddenly changed, nor did it return to its previous level
until some time afterward.

My father sometimes made successful use of the plethysmograph to
discover whether an accused person was guilty of the crime imputed to
him, by mentioning it suddenly while his hands were in the
plethysmograph or placing the photograph of the victim unexpectedly
before his eyes.

_Morbid Phenomena._ When examining a criminal or even a suspected
person, who is nearly always more or less abnormal, it is advisable to
investigate the more common morbid phenomena he may be subject to, on
which he is not likely to give information spontaneously because he is
ignorant of their importance. He should be questioned about his sleep,
whether he has dreams, etc. Mental sufferers nearly always sleep badly
and are frequently tormented by insomnia and hallucinations. The
inebriate imagines he is being pursued by disgusting, misshapen
creatures, from which he cannot escape. Epileptics, and frequently also
hysterical persons have peculiar obsessions. They fancy they cannot
perform certain actions unless they are preceded by certain words and
gestures.

The susceptibility of the patient to suggestion should also be tested,
to determine what value can be attached to his assertions. Sufferers
from hysteria and general paralysis are like children, highly
susceptible to suggestion, not necessarily of an hypnotic nature. If you
tell an hysterical person with conviction that he suffers pain in a
certain part of his body, is feverish or pale or something of the sort,
he will inform you spontaneously after a few minutes that he feels pain
or fever, etc. After a crime of a startling nature has been committed by
some unknown person, it not unfrequently happens that some hysterical
subject, generally a youth, who imagines he has been accused of the
crime by the neighbours or his acquaintances, becomes convinced that he
is really guilty and gives himself up to the police.

_Speech._ Special attention should be directed during the examination to
the way in which the patient replies to questions and his mode of
pronunciation. There may be peculiarities of pronunciation and
stammering, characteristic of certain forms of mental alienation, or at
any rate of some nervous anomaly; or articulation may be tremulous and
forced, as in precocious dementia and chronic inebriety. In other cases
the words are