440 LIVING TORPEDOS IN BERLIN. 



of the reality, I discovered that all these preparations were super- 

 fluous. With a long, broad, straight knife, such as a ham-knife or 

 an English bread-knife, the use of which on the Torpedo I learned 

 from Prof. Fritsch, a strip 5-6 mm. thick can be cut from the 

 organ. This includes only a few columns, and if the cut-surface 

 is applied to strong cardboard it adheres firmly to it. From such a 

 strip, four-sided prismatic bits of the organ can be cut with long- 

 bladed paper scissors which are not too sharp. These four-sided 

 prisms, limited by a bit of skin on the back and belly 5 or 6 

 mm. square, contain a considerable number of columns. Such a 

 portion is placed upon the well-known three-cornered glass plate of 

 the ' Carrier 1 ,' the bottom layers of skin are connected with the 

 clay shields of the conducting pads to which they adhere ; the pads 

 are gently separated so as to draw out the columns to their full 

 length. Such a preparation presents a very clean and neat object 

 of investigation, the length of which naturally depends on the size 

 of the fish and the part of the organ from which it was taken. 

 The longest columns which I manipulated were about 29 mm. in 

 length, and were therefore shorter than the group of muscles from 

 the thigh of the frog. The bundles of columns appeared somewhat 

 thicker. 



My first idea was that the cut surfaces of the preparation would 

 pass through the columns parallel to their axes, not between them, 

 so that the lateral surfaces would be beset by shreds of electrical 

 plates which would either stick to them or to each other, or roll 

 themselves up. But the most careful examination with a lens in 

 fluid failed to discover any such shreds. On the contrary the 

 columns separate themselves from one another under the blades of 

 the scissors with the fibrous sheath undestroyed. It of course 

 sometimes happens that only the upper, under, or middle part of a 

 particular column is attached to the bundle, but these irregularities 

 can easily be got rid of. The shreds of plates if they existed would 

 have no noteworthy electromotive action, or if they had, would 

 retain it only for a veiy short time, so that they would only come 

 into account as affording channels of derivation. 



Such bundles of columns will be used for our experiments on 

 polarisation, which I need hardly say are our most important 

 problems. These experiments take the following form ; as the 



1 Untersuchungen, vol. i. 1848, pp. 495, 496. [Professor du Bois' ' allgemeine 

 Trager ' is an instrument by means of which a preparation may be supported in the 

 moist chamber in any desired position. Tr.] 



