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556 apparatus, and shows that here too it is impossible to find the source of our propensities, instincts, affections, or passions. Finally, he examines the brain itself, and in it discovers the exclusive seat of all these activities. That the passions depend essentially on the brain is proved from the fact that any impairment of that viscus determines a perturbation of the passional no less than of the intellectual phenomena. When we see physicians of half a century ago, who were profoundly versed in the study of insanity—a Pinel or an Esquirol, for instance—hesitate about locating in the brain the immediate cause of dementia and the various forms of mania, we can appreciate the importance of the service done by Gall to the science of man, when he rigorously demonstrated the ill-understood functions of the brain, and proved the correctness of Descartes's doctrine of the passions.

The experiments of modern physiologists, those of Claude Bernard in particular, show that all sensations act primarily on the nerve-centres, through the nerves reaching from the periphery of the body to those centres. The excitation thus determined in the brain, or in the spinal cord, is then transferred to the nerve-filaments which extend to the viscera and members, and hence the latter are affected only secondarily. Of all the organs, the heart is the one which earliest and most profoundly experiences the influence of the sensitive excitations produced in the nerve-centres. So soon as any modification whatsoever is produced in the central nerve-substance, the nerves transmit this vibration to the heart, and at once the movements of the latter suffer a perturbation which is expressed in various ways. At one time the nervous action is sufficiently energetic to at once stop the working of the heart; and, as the blood is no longer discharged into the vessels, syncope (fainting) is the result, the skin assuming the pallor and lividness of death. Again, the reverse effect takes place, the beating of the heart being accelerated, instead of being stopped; in this case the blood is forced through the distended vessels to the brain, and there is over-excitation of that organ's activity. The heart is no more the seat of the sentiments than the hand is the seat of the will, but it is a reactive which is modified by the sentiments, with the utmost nicety and with infallible certainty. Not only does the heart betray, by the very disturbance of its normal rhythm, the nature of the initial brain-excitation, but it also produces throughout the whole organism disordered actions, the sum of which constitutes, as it were, the physical image, the palpable externals of passion. But it produces this disordered action only by reacting on the brain, which is the organ of all the demonstrations and of all the movements of the nerves, and consequently of the muscles. Thus it is that the heart and the brain, the blood-system and the nerve-system, conspire in the production of passional phenomena, by a series of alternate actions and reactions.

Such, are at least, the chief points of Claude Bernard's doctrine, as set forth at a famous Sorbonne conférence, in 1864. At that period the