158 RESPONSE IN THE LIVING AND NON-LIVING 
CHAPTER XVIII 
INORGANIC RESPONSE—INFLUENCE OF VARIOUS CONDITIONS 
ON THE RESPONSE TO STIMULUS OF LIGHT 
Effect of temperature—Effect of increasing length of exposure—Relation 
between intensity of light and magnitude of response—After-oscillation 
—Abnormal effects: (1) preliminary negative twitch; (2) reversal of 
response ; (5) transient positive twitch on cessation of light ; (4) decline 
and reversal— Résumé. 
WE shall next proceed to study the effect, on the re- 
sponse of the sensitive cell, of all those conditions which 
influence the normal response of the retina. We shall 
then briefly inquire whether even the abnormalities 
sometimes met with in retinal responses have not their 
parallel in the responses given by the inorganic. 
Effect of temperature.—It has been found that when 
the temperature is raised above a certain point, retinal 
response shows rapid diminution. On cooling, however, 
response reappears, with its original intensity. In the 
response given by the sensitive cell, the same peculiarity 
is noticed. I give below (fig. 101, a) a set of response- 
curves for 20° C. These responses, after showing slight 
fatigue, became fairly constant. On raising the tem- 
perature to 50° C. response practically disappeared 
(101, 4). But on cooling to the first temperature again, 
it reappeared, with its original if not slightly greater 
intensity (fig. 101, c). A curious point is that while in 
