CHAPTER X 
THE INFLUENCE OF SECONDARY RESISTANCE AND OF 
CATHODE SURFACE 
IN the preceding chapters the scheme for measuring 
break shocks has been developed to the point where it 
becomes necessary to turn from the induction apparatus 
to the tissue to be stimulated and to inquire how varia- 
tions in the tissue may modify stimulation strengths. 
Two possible modifying factors have been indicated 
(p. 14), as due to variations in the tissue; they are sec- 
ondary resistance, and the manner of applying the elec- 
trodes. 
The Relation of Tissue Resistance to Secondary Re- 
sistance as a Whole. The secondary circuit usually has 
a comparatively high resistance. Most indue toria used 
in physiological laboratories have secondary coils with 
resistances mounting into hundreds of ohms, and the 
resistances of the tissues undergoing stimulation are 
usually high likewise. In numerous determinations of 
the resistance of stimulated tissues I have met with only 
one or two under 1000 ohms and have found many ex- 
ceeding 50,000 ohms. 
Since the stimuli imparted by faradic currents as 
71 
