212 PLANT RESPONSE 



At make the kathodic disc was found to become very 

 brilliant, and there was no effect on the anodic. In some 

 instances, indeed, the anode became dimmer than usual, thus 

 showing the depressing influence of the anode. At other 

 times, again, the luminous excitation of the kathode irradiated 

 and encroached upon the anodic region. At break it was 

 the anode which flashed out, showing excitation. These 

 results, as will be seen, are entirely normal. I shall next 

 describe experiments which illustrate the reversed effect 

 .sometimes observed with excessively high E.M.F., and at 

 other times due to a modified condition of the tissue. 



With regard to the production of the reversed effect under 

 a high E.M.F., some difficulty is encountered owing to the 

 proximity of the two discs of the luminous organ. The effect 

 of one electrode is thus liable to encroach on the region of the 

 other. But specimens are occasionally obtained in which, the 

 conducting power of the tissue being feeble, each effect is 

 practically confined to its own area, though the excitatory 

 E.M.F. may be high. 



In the following investigation it is to be noted that 

 successive experiments were carried out on the same speci- 

 men, without disturbing the electrodes. By proper manipula- 

 tion of the key, the current was made to flow now in one 

 direction, then in another, or the acting E.M.F. was changed 

 from low to high at will. The differences of the results 

 observed must therefore have been due, either in the first 

 case to the reversal of anode and kathode, or in the second 

 case to the difference in intensity of the E.M.F. 



A specimen was taken of the detached luminous organ, 

 and electrical connections were made with the two discs, by 

 means of moistened threads. An E.M.F. of ten volts was 

 first used, and the effect at make was a brilliant illumination 

 of the kathode-disc. During the continuation of the current 

 this gradually waned, but at the break of the circuit a 

 brilliant flash appeared at the anode. Thus we have, in the 

 present case, the normal effect with moderate E.M.F. I next 

 used with the same specimen the high E.M.F. of fifty volts. 



