ESTIMATION OF BLOOD-PRESSURE. 241 



the one next the reservoir or heart (h), and the other one 

 (&). Fix the instrument into the nozzles, the bulb A being 

 filled with oil, and in connection with h, B with clefi- 

 brinated blood, and connected with k. The instrument is 

 fixed in position by a support provided with it, while a 

 handle which fits into two tube-sockets on the upper surface 

 of the disc (e, e^ is used to rotate the one disc on the other. 



(c.) All being now ready, take the clamp off the reservoir 

 of blood and the clamps or ligatures off the artery. The 

 clefibrinated blood flows into the bulb A, displaces the oil in 

 it towards B, the defibrinated blood of B being forced out 

 into the artery and caught in a suitable vessel. Of course, 

 in the animal this blood simply passes into the upper end 

 of the artery. As soon as the bulb A is filled with blood, 

 which is indicated by a mark on the glass, the disc is sud- 

 denly rotated, whereby B communicates with h, and A with 

 k. The blood now flows into B, displacing the oil in it into 

 A, and as soon as this takes place, the disc is again rotated. 

 This process is repeated several times. Count the number. 

 The bulbs have the same capacity and are exactly calibrated, 

 so that to measure the amount of blood flowing through the 

 blood-vessel we require to know the time occupied. 



The time is most conveniently measured by connecting 

 the rheometer with an electro-magnet registering on a drum 

 each rotation of the disc, and under this a time-marker 

 records seconds, or a tuning-fork may be used. 



LESSON LV. 



BLOOD-PRESSURE AND KYMOGRAPH- 

 CAPILLARY BLOOD-PRESSURE 

 LYMPH-HEARTS. 



1. Estimation of the Blood-Pressure by Ludwig's Kymograph. 

 As students are not permitted to perform experiments upon 

 live animals, the most they can do in this experiment is to 

 arrange the necessary apparatus as for an experiment, and to 

 make the necessary dissection on a dead animal. 



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