BY DR. BURDON-SANDERSON. 269 



suspensory ligaments of the liver are then severed so as to ex- 

 pose the vena cava inferior. A ligature is passed round that 

 vessel, which is then slit open so as to allow a large canula to 

 pass into the right auricle. The canula having been secured, 

 the liver and lungs are removed, the stomach is severed through 

 the middle, and a stout glass rod, tapering at either end, is 

 passed from the mouth down the oesophagus. This rod should 

 be as large as possible, as the stretching of the parts between 

 the heart and the spinal column which is thus produced mate- 

 rially facilitates their satisfactory exposure. The end of the 

 glass rod which projects from the mouth must then be fixed in 

 a support, and the tube which is inserted in the right auricle 

 be fitted with a flexible tube and connected with a glass reser- 

 voir (for which purpose one of the patent syphon inkstands 

 does best) filled with reddish rabbit serum. The aorta is in 

 like manner connected with a manometer of the form indicated 

 in fig. 233, from which the general arrangement of the heart, 

 reservoir, and manometer will also be best understood. 



The heart is charged with serum and brought into action by 

 filling the reservoir. From thence the liquid fills the right 

 auricle, passes therefrom to the ventricle, and is discharged by 

 it into the manometer. As soon as it is seen that no more air 

 bubbles pass through the proximal limb of the manometer 

 (the upper end of which is 'connected with a flexible tube for 

 the purpose of conveying the liquid pumped by the heart to a 

 suitable receptacle), the apparatus is ready. The mode of ex- 

 periment may be varied according as it is intended merely to 

 measure the variations of endocardial pressure which occur 

 during a cardiac period, or to observe the modifications which 

 that pressure undergoes under different mechanical conditions. 



64. a. Variations of Endocardial Pressure which occur 

 during each Cardiac Period. To observe these, the heart 

 must communicate exclusively with the manometer, the prox- 

 imal limb of which with the tube leading to it from the ven- 

 tricle, and the ventricle itself, must form one cavity filled with 

 serum and closed towards the auricles by the valve, and in 

 the opposite direction by the mercurial column and a clip, by 

 which the tube connected with the upper end of the proximal 

 limb is guarded. The manometer should be at such a height 

 that when the pressure is greatest the top of the proximal 

 column is at the same level as the heart ; and the quantity of 

 mercury it contains must be adjusted, by addition or subtrac- 

 tion, with the aid of a capillary pipette, so that when the heart 

 is in diastole the distal column is still about a millimetre 

 higher than the other. The reservoir for the supply of serum 

 ID u.st now be placed at such a height above the heart that the 

 auricle is equal to that existing during diastole in the ven- 

 tricle ; and inasmuch as this has been alreacty arranged at a 



