172 GENERAL PROPERTIES OF LIVING TISSUES 



The occurrence of idio-muscular contraction 

 (see page 166) is an additional proof of the 

 independent irritability of muscle. 



Irritability and Conductivity are Separate Prop- 

 erties of Nerve. 1. Carbon-dioxide. Arrange 

 the inductorium for tetanizing currents. Connect 

 the secondary coil with the main posts of the 

 pole-changer (cross-wires out). Connect the 



Pig. 42. The gas chamber, with bottle for generating carbon dioxide, 

 and a pole-changer arranged to stimulate the nerve either within or without 

 the chamber. The holes in the glass through which the nerve passes are 

 plugged with normal saline clay. 



two other pairs of posts with the usual stimula- 

 tion electrodes and the electrodes of the small 

 gas chamber (Fig. 42). Join the inflow tube of 

 the gas chamber with the outflow tube of the 

 carbon-dioxide bottle. The gas chamber should 

 rest on a glass plate. Make a nerve-muscle 

 preparation, preserving the full length of the 

 sciatic nerve up to the vertebral column. Tie 



