IV
Boccaccio describes in a masterly manner the effects and changes which love produces on the pulse:
'Thus it happened that he sickened most seriously through excess of passion. Then were several physicians called to restore him, but, despite their careful watching, they could not guess his disease, and despaired of his recovery. And so it came to pass that one day, while a physician, still young indeed, but of profound science, sat near the patient, holding his arm there where the pulse beats, Giannetta came for some reason into the room where the youth was lying, who, when he saw the maiden, did not indeed betray his emotion either by word or gesture, but felt the ardour of passion increase in his heart, wherefore his pulse began to beat more violently than before. This the physician incontinently noticed and wondered, but remained still to see how long these pulsations would continue. When Giannetta left the room, the pulse became calmer. The physician, now deeming he had discovered the reason of the malady, caused the maiden to be called on the pretext of having a question to put to her, he still holding the patient by the wrist. Scarcely had she come into the room than the youth’s pulse beat more rapidly, slackening once more at her departure. Whereupon the physician, believing himself in possession of the truth, arose, and taking the parents of the young man aside, said to them: “The health of your son needs not the physician’s art; it lies in Giannetta’s hands.”'
So Boccaccio describes the diagnosis of the illness of the Count of Antwerp; and long before Boccaccio, Plutarch had already stated that the physician Erasistratus discovered the love of Antiochus to Stratonice from the tumultuous irregularity of his pulse.
We here touch upon one of the greatest problems which criminal science will propound in the future, when it asks the physiologist: 'Tell us of what does this man think, who remains impassive before the traces of his crime? Tell us if within him there is nothing pulsating—nothing, either human or animal?'
Fig. 3.—Curve showing Cardiac Pulsations of a Quiet Dog
I have in my laboratory a dog which was of service to me in a few studies on fatigue. He is such a good animal that for two years I have kept him, together with two other dogs of which I have grown fond, and which, like old friends, shall always stay with me, unless some dog-lover comes to beg them from me, as so often happens with good, faithful dogs, that only in the physiological laboratories can escape from the certain and cruel death to which the Corporation condemns them. As he is a quiet dog, it occurred to me one day to try the effect of a violent noise upon him. I made use of a little instrument called a cardiograph, because it transmits the heart-beats to a lever which traces them on a cylinder covered with smoked paper. I applied this instrument, which is about the size of a half-crown, on the place where the heart beats between the ribs, fixing it by means of an elastic band fastened round the thorax. At first it wrote the curve of the cardiac pulsations represented in fig. 3, which is reproduced by means of photozincography. I regret having to present the reader with more curves, but when one is able to see what the heart itself writes, it would be unpardonable to try to translate its characteristic language into words. Besides, it is not difficult to understand these curves. The line T signifies the time; it is written by an electric clock which raises a pen every second and marks a tooth. It is, so to speak, a controlling line, indispensable in graphic studies by which one wishes to learn with the greatest exactness the changes which the frequency of the pulse undergoes. In the line T eighteen seconds are marked, and the heart-beats registered in the same time in line A amount to twenty-nine. If I had applied the cardiograph to the thorax of a man I should have obtained a similar curve with fewer pulsations. At each beat of the heart the pen rises and falls rapidly, and then writes below a trembling line during which the heart does not beat. As the thorax rises and expands during inspiration, the pen resting on the ribs must likewise rise, therefore the three or four pulsations taking place during the expansion of the thorax are marked successively higher, sinking again with the commencement of expiration, thus forming waves, as it were. From this curve, traced while the animal was tranquil, we see that its heart, as indeed is also the case in man, beats more frequently during inspiration than during expiration, the heart-beats being nearer to each other in the ascending portion of the curve, and further apart in the lower portion which corresponds to the end of each expiration.
While the animal was perfectly quiet I motioned to my servant to fire a gun, but he failed. It was an old hunting-gun, badly loaded perhaps, and only the cartridge had caught fire. The dog, however, at once tried to rise, and became strangely excited, much to our surprise. I had my hands on the instrument which lay on the ribs where the heart beats, and felt that its palpitations had become stronger and more rapid. About a minute later we succeeded in taking the curve B in fig. 4, from which may be seen how much more frequent the pulsations were. The animal had become so restless that we had to give up the experiment and set him at liberty. When he was on the ground he went round the laboratory sniffing everywhere. Presently we took the curve C, fig. 4, from which we can see that the emotion was not yet over, since the beating of the heart is still quicker than in the normal curve marked in fig. 3.
Fig. 4.—Cardiac Pulsation during Emotion
There were several of us together when this experiment was made—the students of the laboratory, my assistants, and Professor Corona, and we were all astonished at what took place. Some of the bystanders said at once that it must be a hound. We had always taken him for a watch-dog, as he was very big, and did not look in the least like a hound. We determined to try a decisive experiment the next day.
We waited till the animal was perfectly quiet, and then held a gun so that he could see it at a distance of a few steps from him, without threatening him in any way. The dog at once recognised the weapon, and again grew excited, showing a considerable change in the cardiac curve.
Fig. 5.—Normal Cardiac Pulsation
But the most evident proof that it was a hound was given by the very violent emotion and the unexpected excitement which took possession of him as soon as he heard the noise caused by the loading of the gun and the click of the trigger. Even when he saw nothing, and this noise was made at some distance from him, the beating of the heart changed instantly (as may be seen in the following curve), and the animal tried to rise and sniffed the air.
The curve D, fig. 5, shows the pulsations written with the cardiograph applied to the thorax of the animal when quiet.
At a given time I signed to a person, whom the dog could not see, to load the gun. Scarcely had the animal heard the clicking than he moved; a few seconds passed, during which it was impossible to take the curve, the dog being so restless. About a minute later I succeeded in obtaining the curve E, fig. 6, in which one can see that the form of respiration, as well as the frequency and force of the cardiac pulsations, is altered.
Fig. 6.—Alteration of the Cardiac Pulsation through Emotion
After we had assured ourselves that these alterations of the pulse were much less marked after other noises which did not resemble the loading of a gun, we wished to convince ourselves whether the agitation was caused by a fear of weapons. The next day the dog was again brought into the laboratory, and while he lay on the table, and the action of the heart was being marked, someone walked past him with a gun on his shoulder. The dog recognised it again, became restless, tried to rise, his heart beat violently, he began to wag his tail, and followed the hunter with satisfied glances.