130 



ADVANCED LESSONS IN PRACTICAL PHYSIOLOGY 



the time. Study the character of the phlebogram, and compare it with 

 the curve of intra-auricular pressure. Under what conditions does the 

 phlebogram become of special value? What changes would tricuspid 

 regurgitation produce in the character of the tracing? 



Obtain a phlebogram in proper relation with a sphygmogram of the 

 radial artery, or with a cardiogram. When would a record of this kind 

 prove of special diagnostic value? 



m 



FIG. 84. PNEUMOGRAPH. (Harvard Apparatus Co.) 



Annotation. As the name indicates, a jugular cup consists of a hemispheric 

 capsule of metal or glass which is placed flat against the region of the central end of 

 the external jugular vein. The pulsations of this blood-vessel are transmitted to 

 a recording drum. 



4. Relation Between the Cardiac and Respiratory Activities. Ad- 

 just a stethograph upon the chest of the subject and connect it with a 

 recording tambour. Place a receiving cup over the region of the carotid 

 artery and connect it with a recording drum arranged to register in the 



FIG. 85. MAREY'S PNEUMOGRAPH. (Verdin.) 



The instrument consists of a tambour (<), mounted on a flexible metal plate (p). By 

 means of the bands c and c the metal plate is tied to the chest. Any increase or decrease 

 in the size of the chest will then affect the tambour by the lever arrangement shown in 

 the figure. These changes in the tambour are transmitted through the tube r as pressure 

 changes in the contained air to a second tambour (not shown in the figure) which records 

 them upon a smoked drum. (Howell.) 



same vertical line as the former. Beneath these writing levers adjust 

 the marker of a Jaquet chronograph. While the subject assumes a 

 perfectly inattentive attitude, record a number of respiratory cycles 

 upon a drum revolving at a moderate speed. How many cardiac cycles 

 does each respiratory cycle embrace? Do you observe an increase in 

 the cardiac frequency on inspiration? Explain this variation. 



Annotation. A simple stethograph may be made by fastening a small rubber 

 pouch by means of a broad linen strap against the chest. The single orifice of this 

 pouch is connected by means of a cannula and a piece of rubber tubing with a record- 



