1901.] on the Response of Inorganic Matter to Stimulus. 



631 



organic are to those of the living substance. We have yet to see 

 whether the similarity extends to this point only, or goes still 

 further. Are the response-curves of the inorganic modified by the 

 influence of external agencies, as the living responses were found to 

 be ? If so, are the modifications similar '? I shall now place two 

 sets of curves side by side, when it will become apparent whether or 

 no similar external influences produce similar results in the two 

 classes of phenomena. 



It has been said that, with rapidly succeeding 

 Effect of stimuli, when the intermittent effects of single 



Superposition shocks are fused, a tetanic condition is produced 

 of Stimuli. in a muscle, and we obtain an almost unbroken 



curve (see U, Fig. 11). If the frequency is not 

 sufficiently great, there is an incomplete tetanus, and the response- 

 curve becomes jagged (see a', Fig. 11). 



a/ 



Fig. 11. — Effects analogous to (a) incomplete and (6) complete tetanus, in tin. 

 (a 1 ) Incomplete and (6 1 ) complete tetanus in muscle. 



The very same thing occurs in metals. I subject the wire to 

 quickly succeeding vibrations. The curve rises to its maximum ; 

 further stimulation adds nothing to the effect, and the deflection is 

 held, as it were, rigid, so long as the vibration is kept up. With 

 lesser frequency of stimulus, we find an incomplete state of tetanus, 

 and the curve becomes jagged (see a and b, Fig. 11). 



It is also curious that the maximum effect is produced almost 



