50 



THE SIGNS OF LIFE 



[LECT. 



and equal deflection to the left. There is no blaze. The eye- 

 ball is dead, or in that state of latent life, or temporary non- 

 living state to which we give the name of " shock." Evidently, 



10 m. 



FlG. 22. Frog's eyeball, induction coil and galvanometer in series. Effects of 

 single break induction shocks in positive and negative directions before and after 

 " electrocution " by strong tetanisation. 



as regards the retina, or the eyeball, the blaze reaction is a 

 very nice and convenient ''sign of life" 



30. The three types. So far, the several experiments that 

 have been grouped together under the head of the third experi- 

 ment (| 26), have come off perfectly well, and, in accordance, 

 with expectation and prediction. 



It might have been otherwise. I took care to be provided 

 with fresh, normal, uncompressed eyeballs, because I did not 

 wish, in introducing the subject, to have to confuse your first im- 

 pression of it by interpolated explanation of unexpected results 

 of experiment. And I was careful to be provided with the 

 lively Rana Tcinporaria, as the sluggish R. csculenta would pro- 

 bably not have answered as well. Nevertheless, I felt it neces- 

 sary to have at my elbow a diagram, in which are schematically 

 summarised the various cases that I have met with in various 

 states of the eyeball. I have divided them into three types : 



