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HYPNOTISM AND ITS PHENOMENA. 67 
condition of the blood, affecting the vitality of the walls of the 
vessels ; but more probably it is largely due to sensory reflex action 
of the nerves.) That this latter seems the commoner mode of action 
would seem to be shown from the fact that emotional influences of 
joy and pleasure with their opposites of sorrow and anger, produce 
their regular effects of heightened circulation in the capillaries in 
the one case, and pallor from spasmodic contraction of the same ves- 
sels in the other. We must here add to this the important factor of 
sympathetic nervous influencef directly exerted upon the heart, pro- 
bably from the vaso-motor centre in the medulla oblongata upon the 
accelerator ganglion in the one instance, and the depressor ganglion 
in the other, both of which have their supposed centres in its muscu- 
lar tissues. 
We now would seem to have sufficient data wherewith to proceed 
in our endeavour to explain the phenomena of hypnotism. We have 
explained the supposed physical conditions tending to produce sleep. 
Have we the same present in induced hypnotism? It seems to me 
that in a large degree we have. It is perfectly well known that the: 
hypnotic state cannot be produced at will in all persons, and in others . 
only with various degrees of ease. It is true, moreover, that persons 
in whom hypnotism can be produced are almost invariably those of © 
an emotional tendency, or those in whom the equilibrium which in 
health exists between the cerebral and spinal systems is most readily 
destroyed—certainly those in whom the sympathetic nervous system 
is most readily acted upon. Nothing can express our views upon 
this point more exactly than the quotation of M. Jaccoud’s remarks 
concerning hysteria. He says: ‘“ The physiological characteristics of 
Hysteria depend upon the importance of the opposing relations which 
exist between voluntary or cerebral innervation, and the involuntary 
or spinal. The performance of the regular functions of the nervous 
apparatus depends upon the natural and innate subordination of 
spinal activity to that of the cerebrum ; this established hierarchy 
(which demonstrates among other things the experimental study of 
reflex motility) is the absolute condition of the normal harmony of 
the nervous functions. Now in hysteria this harmonic equilibrium 
is always broken and always in favour of the spinal cord ; thus is 
produced a disorder which bears fatally upon the collective functions 
of innervation—a veritable cerebro-spinal ataxia which constitutes 
and characterizes the decay of cerebral action, and the predominance 
