144 GENERAL PROPERTIES OF LIVING TISSUES 



with the positive post and the slider. Bring the 

 slider near the positive post. When the sodium 

 carbonate has acted for 15 minutes, bring the 

 cathode against the tibial end, the anode against 

 the pelvic end of the muscle. Close and open the 

 circuit, moving the slider meanwhile to find 

 the current which will give closing contraction. 

 At this point keep the circuit closed. 



Ehythmical contractions usually appear. 



Periodic contractions are observed also in 

 smooth muscle, stimulated with the constant 

 current. Any form of constant stimulus will 

 serve to produce them, pressure as in the 

 heart, bladder, and intestine and chemical 

 action, being especially noteworthy. 



Continuous Galvanic Stimulation of Nerve may 

 cause the Periodic Discharge of Nerve Impulses. 

 If two non-polarizable electrodes are allowed to 

 rest on the muscle (horizontally suspended), and 

 are connected to a capillary electrometer, the 

 meniscus of which is projected through a slit 

 onto rapidly moving sensitized paper, the shadow 

 of the meniscus will make a straight line on the 

 photographic paper so long as- the muscle is at 

 rest. When, however, the nerve of the muscle 

 is stimulated with the galvanic current and 

 closing tetanus appears, the straight line will be 

 broken by 10-15 oscillations per second. These 



