836 



THE CIRCULATION. 



feebly distended artery. This is the dicrotic pulse, which is often 

 present in diseases of a typhoid character. 



116. 



DICROTIC PULJSK OF TYPHOID PNEUMONIA. (Marey.) 

 Fig. 117. 



DICROTIC PULSE OF TYPHOID FEVER (Marey.) 



It is evident that the dicrotic character of the pulse is not, in reality, 

 peculiar to diseased conditions, since the sphygmograph shows that it 

 exists more or less perfectly in a state of health ; only it is too slight 

 in degree to be appreciated by the finger. 



Koschlakoff 1 has succeeded in verifying the results obtained from 

 the sphygmograph, and in demonstrating the mechanism of the dicrotic 

 pulse. He shows that if a liquid be driven by a rapid impulse through 

 an elastic tube, connected with two separate pressure gauges, one 

 situated near the point of entrance of the liquid, the other near its point 

 of exit, the liquid will rise in the first gauge before the increased pres- 

 sure reaches the second ; that it then falls while the second is rising, 

 and again rises while the second falls ; showing an alternate increase 

 and diminution of pressure in the two extremities of the elastic tube. 

 This alternation continues until the pressure is equalized, or until the 

 tube is again distended by a new impulse. 



Pulsating Movement of the Blood in the Arterial System. Owing to 

 the alternate contraction and relaxation of the heart, the blood passes 

 through the arteries in a series of impulses ; and the hemorrhage from 

 a wounded artery is distinguished from venous or capillary hemorrhage 

 by the fact that the blood flows in successive jets, as well as more 

 rapidly and abundantly. If a slender canula be introduced through the 

 walls of the left ventricle, in the exposed heart of a living animal, the 

 flow of blood from its external orifice is seen to be completely intermit- 

 tent. A strong jet takes place at each ventricular contraction, and at each 

 relaxation the flow is interrupted. If a puncture be made, however, in 

 any of the large arteries near the heart, the flow of blood through the 

 opening is no longer intermittent, but continuous ; only it is much 

 stronger at the time of the ventricular contraction, and diminishes, 

 though it does not entirely cease, at the time of relaxation. If the 

 blood were driven through rigid and unyielding tubes, its flow would 



1 In Lorain Etudes de MSdecine Clinique. Paris, 1870, p 75 



