PULSE-MOVEMENT. 



sure. After repeated experiments, however, Wundt was led, as a result of ex- 

 perimental observations, to the conclusion that blood-vessels also are subject to 

 the general law of elasticity mentioned. He maintains that it is necessary to take 

 into consideration not only the first distention that occurs after the application 

 of the load, but also the "elastic after-effect" that follows gradually. 



This terminal distention, which often proceeds slowly, is so gradual during the 

 last moments that observation with a magnifying lens is necessary to determine 

 when the condition of definitive distention is completed. Deviations from the 

 general law occur; for when a certain load is exceeded, lesser degrees of distention 

 and at the same time permanent changes not infrequently result. A normal vein 

 may be stretched at least 50 per cent, without exceeding the limit of elasticity. 



Pathological. Nutritive disturbances modify the elasticity of the arteries. 

 When death has been preceded by marasmus, the arteries are found relatively 

 more dilated than under normal conditions. Beginning connective-tissue forma- 

 tion in the intima, combined with fatty degeneration, at first increases the dis- 

 tensibility and diminishes the strength of the wall. As the development of the 

 connective tissue progresses in cases of arteriosclerosis, the elasticity and firmness 

 of the arteries are again augmented. Diminished distensibility is found also in 

 connection with atheroma, in cases of nephritis and in the arteries of drunkards. 



A property peculiar to the walls of the blood-vessels is their power 

 of cohesion, which enables them to resist rupture, even when the in- 

 ternal tension is considerable. It has been found that the carotid 

 artery does not rupture until the internal pressure has been raised 

 artificially to fourteen times the normal. The resistance of veins to 

 rupture is relatively greater than that of arteries with the same thick- 

 ness of wall. According to Grehant and Quinquaud the carotid and 

 iliac arteries in man resist a pressure up to eight atmospheres and the 

 veins more than half of this amount. 



Pathological. Diminished power of cohesion of the blood-vessels, especially 

 the arteries, is not uncommon in old age. 



PULSE-MOVEMENT. TECHNIC OF PULSE-EXAMINATION. 



The physicians of antiquity devoted more attention to abnormal excitation 

 of the pulse than to the normal pulse. Thus, Hippocrates (460-377 B. C.) speaks 

 only of the former condition and applies to it the term ojvyptf. Later, 

 Herophilus (300 B. C.) in particular compared the normal pulse (Trafy6fi 

 with the abnormally excited pulse. He laid especial stress on the time-relations 

 existing between dilatation and contraction of the arterial tube and defined more 

 accurately the properties, volume, fulness (a^vy^ raxvg) and frequency 

 (a<j)vyfj.6g TTVKVO^) . His Alexandrian colleague Erasistratus (who died 280 B. C.) 

 was the first to make correct statements in regard to the propagation of 

 the pulse-waves; for he stated distinctly that the pulse appears earlier in the 

 arteries nearer the heart than in the more distant vessels. Erasistratus also felt 

 the pulse below a cannula introduced in the continuity of an artery. Archigenes 

 claims especial interest, particularly with respect to the pathology of the pulse, 

 because he was the first to designate the dicrotic pulse, which he had the oppor- 

 tunity of observing in febrile diseases. Galen (131-202 A. D.) determined more 

 accurately than his predecessors the principles governing expansion and contraction 

 of the arteries during the movement of the pulse. His explanation of the slow 

 pulse was that the time of expansion was prolonged. Galen made also note- 

 worthy observations with regard to the rhythm of the pulse and the effect of 

 temperament, sex, age, season of the year, climate, sleep and waking, emotional 

 influences, and cold and warm baths. Cusanus (1565) was the first to count the 

 pulse-beats with a time-piece. 



INSTRUMENTS EMPLOYED IN THE EXAMINATION OF THE PULSE. 



It is possible by means of instrumental examination to obtain trustworthy 

 information with regard to the nature of the movement of the pulse. Apart from 

 those instruments by means of which the undulatory movement in the arterial 

 tube can be demonstrated only after this has been opened, the following are 

 worthy of mention: 



