On the Electric Organ in Malapterurus electricus. 443 



instead of a battery, the potential being kept low until a balance is 

 nearly obtained. Square blocks of the organ of various dimensions 

 were placed cn a glass slip, and broad cables of lamp-wick pasted over 

 with kaolin and salt solution used to connect them with the ordinary 

 non-polarisable electrodes. After each measurement the cables were 

 joined together without the interposition of the organ strip, in order 

 to ascertain the resistance due to the leads. It was found that the 

 variation in resistance of the leads between one experiment and 

 another was relatively inconsiderable, the greater part of the electrode 

 resistance being evidently due to the unexposed portions of the non- 

 polarisable electrodes, i.e., the tubes containing saturated zinc sulphate. 

 The direction of the current was reversed from time to time, but such 

 reversal was not found to exercise any marked influence upon the results. 



The differences in the extensibility and elasticity of the superficial 

 and deep boundary walls of the organ offered a difficulty, since it was 

 found to be almost impossible to cut the organ into blocks which 

 should be of the same superficial area on these two aspects. Care 

 was, however, taken that in every case the dimension in the direction 

 of the length of the columns (i.e., head end to tail end) should be, if 

 anything, less than that in the direction across the length of the 

 columns (i.e., transverse). These two dimensions will for brevity be 

 termed, the first, longitudinal, the second, transverse, the words indi- 

 cating their relationship to the organ column. 



It must be remembered that the line of flow of a current directed 

 longitudinally is transverse to all the flattened discs which are placed 

 athwart the columns — whilst that of a current directed transversely 

 to the column is parallel with these thin discs. On primd facie grounds 

 we should expect that the resistance in the former case would be far 

 larger than that in the second if, as seemed certain, the thin disc sub- 

 tance has an electrical resistance which is far above that offered by the 

 remaining space of the compartment and the albuminous substance 

 with which this is filled. 



This expectation was fully realised by the experimental results, of 

 which the following table gives examples : — 



Eesistance of Block of Electrical Organ. 



Dimensions. 



Resistance. 



Longitudinal. 



Transverse. 



Thickness. 



To longitudinal 

 current flow. 



To transverse 

 current flow. 



mm. 

 10 

 15 

 12 



mm. 

 10 

 15 

 13 



mm. 

 3 

 3 

 3 



olims. 

 2700 

 2800 

 3100 



olims. 



600 

 1300 

 1300 



