Fear . ch I have grown fond, andwhich, like old friends, shall always stay with me,unless some dog-lover comes to beg them from me, asso often happens with good, faithful dogs, that onlyin the physiological laboratories can escape from thecertain and cruel death to which the Corporationcondemns them. As he is a quiet dog, it occurred tome one day to try the effect of a violent noise uponhim. I made use of a little instrument called a cardio- THE BEATING OF THE HEART 109 graph, because it transmits the heart-beats to a leverwhich traces them on a cylinder covered with smokedpaper. I applied thi
Fear . ch I have grown fond, andwhich, like old friends, shall always stay with me,unless some dog-lover comes to beg them from me, asso often happens with good, faithful dogs, that onlyin the physiological laboratories can escape from thecertain and cruel death to which the Corporationcondemns them. As he is a quiet dog, it occurred tome one day to try the effect of a violent noise uponhim. I made use of a little instrument called a cardio- THE BEATING OF THE HEART 109 graph, because it transmits the heart-beats to a leverwhich traces them on a cylinder covered with smokedpaper. I applied this instrument, which is about thesize of a half-crown, on the place where the heartbeats between the ribs, fixing it by means of an elasticband fastened round the thorax. At first it wrote thecurve of the cardiac pulsations represented in fig. 3,which is reproduced by means of regret having to present the reader with more curves,but when one is able to see what the heart itself writes,. Fig. 3.— Cuiive showing Cardiac Pulsations of a Quiet Dog it would be unpardonable to try to translate its cha-racteristic language into words. Besides, it is notdifficult to understand these curves. The line T sig-nifies the time ; it is written by an electric clock whichraises a pen every second and marks a tooth. It is, soto speak, a controlling line, indispensable in graphicstudies by which one wishes to learn with the greatestexactness the changes which the frequency of thepulse undergoes. In the line T eighteen seconds aremarked, and the heart-beats registered in the same IIO FEAR time in line A amount to twenty-nine. If I hadapplied the cardiograph to the thorax of a man Ishould have obtained a similar curve with fewer pul-sations. At each beat of the heart the pen rises andfalls rapidly, and then writes below a trembling lineduring which the heart does not beat. As the thoraxrises and expands during inspiration, the pen restingon the ribs must likewise rise, therefore
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbrain, bookyear1896
