REVIEW OF RESPONSE OF ISOTROPIC ORGANS 689 



at this stage induces little further excitatory distortion, while 

 the tendency to recovery is great. In this fatigue-state the 

 amplitude of response undergoes a decline, and in the 

 succeeding stage E an actual reversal 



The various corresponding types of response sub-tonic 

 abnormal, staircase, uniform, fatigue-decline, and fatigue- 

 reversal are not exhibited by any one particular kind, but 

 by all forms of tissues. Thus muscle may exhibit a short- 

 lived staircase effect, and nerve, supposed to be indefatigable, 

 not only shows decline, but even reversal of normal response, 

 under extreme fatigue. 



There are two definite conditions under which the normal 

 negative response is converted into abnormal positive, with 

 an intermediate diphasic. These are (i) the condition of 

 extreme sub-tonicity, and (2) that of fatigue brought on by 

 over-stimulation. As regards the first, it is to be remem- 

 bered that the normal excitability of a tissue is maintained 

 by the supply of energy from the rest of the organism of 

 which it forms a part. Under isolation, the latent energy or 

 tonic condition of the tissue is liable to fall below par, under 

 which circumstances the response becomes abnormal positive. 

 By the absorption of the energy of stimulus, the substance is 

 transformed from the A to the B condition, with restoration 

 of its normal response. The process of gradual trans- 

 formation may be seen in a series of records to successive 

 stimuli, when the abnormal gradually passes into the normal, 

 through an intermediate diphasic. Or, an intervening 

 tetanisation will serve to convert response from the abnormal 

 to the normal. Abnormal or reversed response is also seen 

 to occur under fatigue, but its genesis in the molecular curve 

 is here in reversed order to that of the abnormal response of 

 sub-tonicity. In the latter, during the continuous trans- 

 formation from the A to the C phase, stimulation converted 

 the abnormal response into normal, through diphasic. But 

 now, during transformation induced by stimulus- from C to E, 

 the normal negative passes into abnormal positive, through 

 intermediate diphasic. To transform the abnormal positive 



Y Y 



