CHAPTER VIII 



VARIOUS TYPES OF RESPONSE 



Chemical theory of response Insufficiency of the theory of assimilation and dis- 

 similation Similar responsive effects seen in inorganic matter Modifying in- 

 fluence of molecular condition on response Five molecular stages, A, B, C, D, E 

 Staircase effect, uniform response, fatigue No sharp line of demarcation 

 between physical and chemical phenomena Volta-chemical effect and by- 

 products Phasic alternation Alternating fatigue Rapid fatigue under con- 

 tinuous stimulation In sub-tonic tissue summated effect of latent components 

 raises tonicity and excitability Response not always disproportionately greater 

 than stimulus Instances of stimulus partially held latent : staircase and ad- 

 ditive effects, multiple response, renewed growth Bifurcated responsive ex- 

 pression. 



ACCORDING to current theories, living matter is maintained 

 in a state of equilibrium by the two opposed chemical pro- 

 cesses of assimilation and dissimilation. It is supposed that 

 stimulus causes a down or dissimilatory change, which is 

 again compensated during recovery by the building-up or 

 assimilative change. In the case of uniform responses, again, 

 these two processes are regarded as balancing each other. 

 On this theory, when the down change is the greater of the 

 two, the potential energy of the system falls below par ; for 

 the building-up process cannot then sufficiently repair the 

 chemical depreciation caused by it. Hence occurs dimi- 

 nution of response, or fatigue, which is supposed to be further 

 accentuated by the accumulation of deleterious fatigue-stuffs. 

 The disappearance of fatigue after a period of rest is ex- 

 plained by the renovating action of the blood-supply, which 

 is also regarded as the means of carrying away the fatigue- 

 stuffs. 



A serious objection to these explanations lies, however, 

 in the fact, that even excised and bloodless muscles exhibit 

 recovery from fatigue after a period of rest. In isolated 



