690 COMPARATIVE ELECTRO- PHYSIOLOGY 



into normal negative in the first case, stimulation is necessary. 

 To do the samein the second case, rest is necessary. In 

 the records obtained from different animal tissues, various 

 anomalies are met with, of which there has not hitherto been 

 any satisfactory explanation. Thus the same tissue at 

 different times will be found to give either the normal 

 negative, or di-phasic, or abnormal positive response. Thus 

 it has been shown that in the two extreme cases alike, of sub- 

 tonicity and fatigue, the response of nerve is abnormal positive 

 (p. 636). Numerous other examples of this fact have been met 

 with in the course of this work, in, for example, the response 

 of skin (p. 311), that of the glandular and digestive organs 

 (pp. 342, 346), and that of retina (p. 423). It will thus be 

 seen how important is the molecular condition of the tissue 

 in determining the nature of response. This is strikingly 

 shown in the fact that the same tetanisation which in the A 

 condition converts the abnormal to normal, in the D will 

 convert the normal into abnormal. Again, if tetanisation be 

 applied at the beginning of the B stage, the subsequent re- 

 sponses are enhanced, whereas the same tetanisation at the 

 end of C induces a fatigue reversal (figs. 394, 395, and 398). 



That the explanation of these various results is to be 

 sought for in molecular considerations, and not in that hypo- 

 thetical assimilation and dissimilation which really explain 

 nothing, is fully demonstrated by the fact that precisely 

 similar responsive variations are obtained, in the same cir- 

 cumstances, in the case of inorganic matter, under different 

 forms of stimulus and different methods of record. As an 

 j, example, may be cited the transformation of abnormal 

 response into normal, in tungsten, after tetanisation (fig. 

 391), the stimulus employed being electric radiation, and 

 ; the mode of record, resistivity-variation. Parallel effects have 

 Hbeen shown in the case of tin, the response being recorded 

 I Iby the electro-motive variation, and the stimulus employed 

 J (mechanical (fig. 386). The enhancement of normal response 

 also under tetanisation, when at the B stage, has been shown 

 in tin (fig. 388); and finally, the reversaLof normal response 



