206 



Canadian Record of Science. 



account of the differences in pressure in the two kinds of 

 vessels. 



My experiments were all performed on dogs, which 

 first received an injection of morphine, and were then 

 thoroughly anaesthetized with a mixture of equal parts of 

 chloroform and ether. 



Fig. 1. — Pressure tracing from artery (below) and femoral vein (above). 

 Time \ seconds. From a dog. 



Pulse tracings were taken on a blackened surface sim- 

 ultaneously from two points on the veins. At the same 

 time a chronograph was arranged to mark seconds or 

 fifths of seconds on the recording surface, so as to indicate 

 the rate at which it was moving. By this means it was 

 possible to estimate the time elapsing between the appear- 

 ance of a certain wave on the tracing taken from a vein 

 at a point near the heart, and on that taken farther away 

 from the heart. Then, in order to estimate the I'ate at 

 which a given pulse wave travelled, it was only necessary 

 to know, in addition, the distance of the points on the 

 veins from one another measured along the line of blood 

 flow, or more exactly the difference in the distances of the 

 two points from the heart (right auricle). 



The recording surface employed was that of Hurthle's 

 large clockwork kymograph. 



The pulse waves were recorded by inserting a fine glass 

 canula, with a long drawn out point, into the vein through 

 a side branch. (See Fig. 3.) The canula was then con- 

 nected by rubber tubing with one of Hurthle's venous 

 manometers, which marked the waves on the surface of 

 the kymograph. 



