CELLS TO SECRETE ELECTRICITY. 227 



seen in German towns. John Hunter, who puhHshed 

 an exhaustive paper on the anatomy of the torpedo, in 

 " Philosophical Transactions for 1773," gives the num- 

 ber of these columns to be about 470 in each conglome- 

 rate mass — the longest column being about liin., the 

 shortest about the fourth of an inch, and in diameter 

 about two -tenths of an inch. The ultimate structure 

 of these columns can be seen in the wax models of 

 the structure of the torpedo at the Koyal College of 

 Surgeons ; these magnificent demonstrations of struc- 

 ture were made by Professor Calamai of Florence, and 

 presented by His Imperial and Koyal Highness the 

 Grand Duke of Tuscany to Professor Owen, and by hiin 

 to the Eoyal College of Surgeons, January, 1850. 



If we can imagine one of the series of the cells 

 broken off and held up to the light, we should have the 

 appearance of a single cell of a honeycomb — the wax 

 walls being represented by a gelatinous membrane, 

 thinner than goldbeater's skin ; inside the cell may be 

 seen, not honey, but a jelly-like transparent fluid. Wo 

 shall also see that a membrane, thinner still than that 

 which composes the walls, divides the contents of the 

 cell into a series of chambers. Upon these transverse 

 septa, or partitions, the microscope would show the 

 most marvellous ramifications of the blood- carrying 

 capillaries ; and the ultimate meshes of the great 

 electric nerves will be found to have spun themselves, 

 as it were, into a network, with complicated meshes, 

 far exceeding any cobweb in tenuity and minuteness. 

 The interval between the transverse plates. Professor 

 Wyman states, is occupied by a fluid, consisting of 

 about ninety per cent, of water, containing albumen 

 and common salt. 



Next will be observed four enormous cord-like nerves; 



