Page:Popular Science Monthly Volume 4.djvu/576

558 painful loss, when suddenly conveyed, oftentimes produces wild, irregular contractions, owing to a paralysis of the retardator nerves, and it is not rare to find this disordered excitation followed by a total stoppage of the heart's action, and syncope. Hence, says Claude Bernard, when we have to communicate to a person some heart-breaking piece of intelligence, we must use great precaution. The intensity of the effects produced on the heart by the soul's emotions depends, above all, on the excitability of the nerves connecting heart and brain. The greater the excitability of these nerves, the more pronounced are the heart's motions, and the finer, too, and the more delicate are the consecutive impressions. It is because the nerves of women and children are more excitable than those of men, that their hearts also are more profoundly affected by the emotions; or, in common language, their hearts are more tender, more sensitive.

While the heart seems to be more directly under the influence of the feelings, the lungs appear to have some connection with thought. When absorbed in some profound meditation, or when listening to some orator whose discourse rivets our attention, we suspend the respiratory movements. Darwin offers an ingenious explanation of this phenomenon, attributing it to the habit we have contracted of not breathing when we are listening attentively, so as not to disturb by the sound of the breath the silence necessary for catching every syllable.

From the fact that the real affections of the soul, and consequently of the brain, are always accompanied by disturbance of the respiratory and circulatory functions, we may conclude that the heart and the arterial tension are the true index of the passional states. Hence it is that the actor, when he would prove that some perilous situation inspires him with no fears, seizes the hand of the one he seeks to reassure or to convince, and places it over his own heart, in order to show that the beatings of that organ keep up their usual rhythm. Hence, too, it is that we must not regard outcries and gestures as positive indices of passion. When you see a woman weeping and agitated on hearing some painful news, you have only to feel her pulse; if that is normal, you may pronounce the emotion simulated. On the other hand, if you see a woman whose distress is manifested by no outward signs, but whose heart beats with unwonted irregularity, you may be sure that she feigns a calm that is not in her soul. There is yet another mode of ascertaining, and even of measuring accurately, the strength of emotions. This we may do by applying either to the pulse or to the heart one of those delicate apparatus invented by M. Marey, which trace on a sheet of blackened paper curves of greater or less sinuosity, representing the number, the force, and the form of the beats of the pulse, or the contractions of the heart. Just as these apparatus give us tracings which at once indicate the nature of the heart's motions in various diseases, for instance, fever, typhus, or