444 On the Electric Organ in Malapterurus electricus. 



The resistance to the flow of a current in the longitudinal direction 

 (i.e., directed across the disc surfaces) is thus from two to three times 

 as great as that offered by the organ to the flow of a current in the 

 transverse direction (i.e., directed parallel to the disc surfaces). The 

 discs themselves thus offer, when their physiological condition is unim- 

 paired, a high resistance as compared with the adjoining compartmental 

 contents, and this result is corroborated by experiments made after the 

 conditions had been modified either physically or physiologically. The 

 physical modification consisted in taking blocks, the longitudinal 

 dimensions of which varied. Thus a block 10 mm. in the transverse 

 dimensions and 3 mm. in thickness, was cut so as to be 90 mm. in the 

 longitudinal dimension. Its resistance to the flow of a longitudinal 

 current amounted to 27,600 ohms. On reducing its length to 40 mm. 

 the resistance was 13,000; on reducing it to 20 mm. it was 5700, and 

 on reduction to 10 mm. it was 2700 ohms. The heavy longitudinal 

 resistance is seen to increase in proportion to the length of the columns, 

 and the results thus indicate that our method was a fairly accurate 

 one. 



The physiological modifications were produced both by destroying 

 the living condition of the fresh tissue by a suitable rise of tempera- 

 ture and by keeping the tissue in physiological saline for a number of 

 hours, so that the living condition should be more or less replaced by 

 one due to commencing natural death. 



In the case of destruction through heat, the striking discrepancy 

 between the large resistance offered to longitudinal currents, and the 

 lower one offered to transverse ones, always disappeared completely. 

 The resistance was now found to be the same whatever the direction 

 of the current flow. 



In the case of kept preparations, the disparity between the two 

 resistances became so much the less marked as the preparation lost 

 its living characteristics ; thus a preparation which had been kept 24 

 hours in saline still showed 1500 ohms longitudinal resistance, as 

 compared with 500 ohms transverse ; whilst a second strip, kept for 

 48 hours, showed only 1000 ohms longitudinal, as compared with 800 

 ohms transverse. 



There is thus little doubt that the greater resistance offered by the 

 columns of the fresh organ to longitudinal flow of currents is due to 

 the circumstance that these are directed through the protoplasmic 

 substance of the thin plates or discs, which, lying directly athwart 

 the columns, are all so interposed in the line of flow as to give a 

 maximum of protoplasm to be traversed by such a flow. On the other 

 hand the small resistance offered to transversely directed currents is an 

 expression of the fact that the flattened protoplasmic discs now form 

 but an insignificant portion of the conducting medium, which is chiefly 

 composed of the compartment spaces. The discs must therefore have 



