TORPEDO RAY. 311 



tendinous fibres, passing transversely and ob- 

 liquely between the columns, and uniting them 

 more firmly together. These are mostly observable 

 where the large trunks of the nerves pass. The 

 columns are also attached by strong inelastic fibres, 

 passing directly fi^om the one to the other. The 

 number of columns in different Torpedos of rather 

 small size, appears to be about 470 in each organ, 

 but the number varies according to the size of the 

 fish; and in a very large Torpedo the number of 

 columns in one electric organ was J 182. They 

 must therefore increase, not only in size but in 

 number, during the growth of the animal, new ones 

 forming perhaps every year on the exterior edges, 

 as they are much the smallest. This process may 

 be similar to the formation of new teeth in the 

 human jaw, as it increases. Each column is divid- 

 ed by horizontal partitions, placed over each other 

 at very small distances, and forming numerous 

 interstices, which appear to contain a fluid. These 

 partitions consist of a very thin membrane, con- 

 siderably transparent. Their edges appear to be 

 attached to one another, and the whole is attached 

 by a fine cellular membrane to the inside of the 

 columns. They are not totally detached from one 

 another ; and I have found them adhering at differ- 

 ent places, by blood-vessels passing from one to 

 another. The number of partitions contained in a 

 column of one inch in length, of a Torpedo which 

 had been preserved in proof spirit, appeared, upon 

 a careful examination, to be one hundred and 

 fifty : and this number, in a given length of column 



