208 



EXPEPUMENTAL PHYSIOLOGY 



the other side is another knob on the end of a bar, b', for adjustment to the 

 corresponding point on the opposite side. An increase in diameter leads to 

 a separation of the two knobs, only one of which can move relatively to the 

 framework. This drives air out of the tambour and causes a rise of the lever 

 of the recording tambour. The most important diameters to employ are (1) 

 that which connects the 8th rib in the axillary line with the same rib of the 

 opposite side, and (2) that from the lower end of the sternum to the 8th 

 dorsal spine. 



Eecord the changes in these two positions (1) during quiet breathing, 

 (2) while sipping a glass of water, and (3) while swallowing a mouthful of 

 biscuit. 



The results obtained will be similar to those reproduced in fig. 168, 

 which were taken with the instrument recording changes in the trans- 

 verse diameter of the thorax. It is seen that inspiration and expiration 

 each occupied about the same time ; that at first the movement is rapid 



Fig. 168. — Eecord of Changes in the Transverse Diameter of the Thorax 

 during Eespiration (Man). The Upper Curve taken during Quiet Breath- 

 ing : the Lower Curve shows the Effect of Swallowing. Time Tracing 

 Seconds. 



in either direction, and then gradually slows. In the lower of the two 

 tracings the inhibition of respiration during swallowing is recorded. 

 A glass of water was slowly swallowed, and respiration was at once 

 inhibited at the commencement of expiration, remaining in that state 

 until swallowing ceased, when a fresh and rather deeper inspiration 

 followed. From this time respiration resumed its usual characters. 



