32 



THE SIGNS OF LIFE 



[LECT. 



coats. A fresh eyeball prepared with such care as to give the 

 typical positive response of the first type can at once be made 



r\ 



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FlG. 15. Diagram to illustrate the effect upon a galvanometer 

 (broken line) of a simultaneous larger positive current and smaller 

 negative current, the latter commencing and ending more rapidly. 



FlG. 15. Retinal response of the second stage, illustrating 

 the double effect. 



to give the negative response of the third type by gentle massage 

 by steady moderate compression, and in the latter case it is 



or 



