556 THE POPULAR SCIENCE MONTHLY. 



apparatus, and shows that here too it is impossible to find the source 

 of our propensities, instincts, affections, or passions. Finally, he ex- 

 amines 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 whatso- 

 ever 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 liv- 

 idness 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-ex- 

 citation, but it also produces throughout the whole organism disor- 

 dered actions, the sum of which constitutes, as it were, the physical 

 image, the palpable externals of passion. But it produces this disor- 

 dered action only by reacting on the brain, which is the organ of all 

 the demonstrations and of all the movements of the nerves, and conse- 

 quently of the muscles. Thus it is that the heart and the brain, the 

 blood-system and the nerve-system, conspire in the production of pas- 

 sional 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 conference, in 1864. At that period the 



