CHAPTER XXII 



RESPONSE OF ANIMAL AND VEGETAL SKINS 



Currents of rest and action Currents in animal skin Theories regarding these 

 Response of vegetal skin Stimulation by Rotary Mechanical Stimula- 

 tor Response of intact human skin Isolated responses of upper and 

 lower surfaces of specimens Resultant response brought about by differ- 

 ential excitability of the two surfaces Differences of excitability between 

 two surfaces accounted for Response of animal and vegetal skins not 

 essentially different General formula for all types of response of skin 

 Response of skin to different forms of stimulation gives similar results 

 Response to equi-alternating electric shocks : (i) Method of the After Effect ; 

 (2) Method of Direct Effect Response of grape skin Similar response of 

 frog's skin Phasic variation of current of rest induced as result of 

 successive stimulation in (a) grape skin ; (b) frog's skin ; (c] pulvinus of 

 Mimosa Phasic variation in autonomous mechanical response of Des- 

 medium gyrans Autonomous variation of current of rest True current of 

 rest in skin from outer to inner This may be reversed as an excitatory 

 after effect of preparation Electrical response of skin of neck of tortoise 

 Electrical response of skin of tomato Normal response and positive after- 

 effectResponse of skin of gecko Explanation of abnormal response, 



IN this and the next few chapters it is my intention to make 

 an inquiry into the responsive peculiarities of the skin, 

 epithelium, and glandular tissues, alike in plant and animal. 

 By the study of such simple cases as are found in plants, it 

 should be possible to obtain' a clear insight into the various 

 factors which go to make the corresponding phenomena 

 in animal tissues so complicated and obscure as to be 

 difficult of reconciliation with each other. 



It is not possible in a short space to give any but the 

 briefest summary of the work hitherto done on this extended 

 subject in animal physiology. All that can be attempted is 

 to indicate some of the leading theories and x results, at the 

 same time drawing attention to those outstanding questions 

 which still remain open. Some of the methods which I have 



