1902.] 



" Blaze-currents " of the Crystalline Lens. 



195 



times found to give a larger response than the posterior half, and the 

 present observations proceed from an attempt to determine the princi- 

 pally effective part in such reaction. And I may state at once, as my 

 chief conclusion, that it is the crystalline lens. 



The eyes upon which the determination was made, in the first 

 instance, were those of fish — whiting and mackerel — by reason of the 

 fact that these were for a season at my disposal quite fresh from the 

 sea. I subsequently made similar observations on the eyes of octopus, 

 on sheep's eyes fresh from the slaughter-house, and on the eyes of 

 recently killed cats and rabbits ; also on the eyes of an owl. 



The point that was most striking in these first observations was the 

 great endurance of the reaction in the crystalline lens as compared 

 with its rapid disappearance from the remaining tissues of the eyeball 

 and from the skin, and with the rapid disappearance of the direct 

 electrical excitability of muscle. I should, as an outcome of these 

 observations, look for the last sign of life of a fish by testing the 

 crystalline lens, whereas in the case of man I should test a piece of 

 skin. The reaction — as far as I have yet seen — has been completely 

 absent from frozen fish (salmon) as received from London fishmongers. 

 Its normal direction in the lens is " negative," i.e., from external to 

 internal pole. It is abolished by heat (70°) and by compression. . 



My first experiments with the eyes of fish were to ascertain on the 

 entire eyeball what type of blaze reactions — if any — is manifested 

 The results were as follows : — 



Exp. 1. Whiting. — Excit. and lead-off through AB. Berne 

 coil. Two Leclanches in primary circuit. Singie break A 

 induction shocks. 



1000+ gave -0*0004 volt. 

 1000- „ -0-0007 „ 

 5000+ „ -0-0010 „ 

 5000 - „ -0-0017 „ 



Reactions after immersion in hot water. 



5000 + gave nil. 

 5000 - „ 



Exp. 2. JVhiting. — Excit. through AB and lead off 

 through BC or AC. (The system of notation is ex- 

 plained in the ' Roy. Soc. Proc.,' vol 69, p. 



183.) 



500O- 

 5000 + 



-O'OOlO 

 -O-0O05 



5000 - 

 5000 + 



nib 



nib 



