Eight lectures on the signs of life from their electrical aspect eightlectureson00wall Year: 1903 •] TETANISATION AND ILLUMINATION 55 response to light by strong tetanisation, and vice versa for modi- fications of the response to induction shocks by strong illumina- tion, I also took series of positive responses to light and to weak tetanisation alternated, to see whether or no they would decline pari passu. An example of such a series has been Fig. 24.—Frog's eyeball. Series of normal responses to light and to tetanisation alternated ; each excitation lasts for one minute. The response t
Eight lectures on the signs of life from their electrical aspect eightlectureson00wall Year: 1903 •] TETANISATION AND ILLUMINATION 55 response to light by strong tetanisation, and vice versa for modi- fications of the response to induction shocks by strong illumina- tion, I also took series of positive responses to light and to weak tetanisation alternated, to see whether or no they would decline pari passu. An example of such a series has been Fig. 24.—Frog's eyeball. Series of normal responses to light and to tetanisation alternated ; each excitation lasts for one minute. The response to tetanisation falls more rapidly than that to light. figured above. The series of responses to tetanisation appears to decline more obviously than does the series of responses to light. But the difference is not very striking, and in other records it is even less so. In fact, when I took the records, I thought they justified me in saying that the two kinds of response wear out in a parallel manner. Clearly, however, the parallelism has not always if ever been absolute ; the instance figured above exhibits more rapid decline of the tetanisation responses than of the light responses. The point clearly needs to be tested again. As regards modification of the response to induction shocks by strong illumination, we have seen that no appreciable effect occurs. As regards modification of the response to light by strong tetanisation, we have seen that the regular effect has been an increased response during and after tetanisation. Indeed, the resistance of the retina as regards its excitability by light has been a constant yet surprising feature. The strongest tetani- sation at my disposal (Berne coil, 2 Leclanches, secondary over primary coil, current unbearable by wetted fingers) has failed to abolish its response to light. And strong tetanisation (10,000 units) that has completely abolished all blaze-reaction (as ^
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