THE ELASMOBRANCH FISHES 115 



the presence of cells with enormous nuclei. The middle striated layer consists 

 of fibers probabl}^ of connective tissue which take a transverse and wave-like 

 course. In this, nuclei are rarely seen. The inner or alveolar layer is at first 

 composed of granular tissue which later gives rise to long, backward directed 

 projections. At the base of these three layers is a thick cushion of gelatinous 

 tissue which is contained in the connective tissue walls of the cone. 











f|if jj/ " 



Fig. 118. Electric organ, Torpedo. (After Scbimkevitsch from Krupski's atlas.) 



eJ.c, electric columns. 



In the adult organ of Torpedo, the discs, as previously noted, are located in 

 the body in the region of the pectoral fins. Removal of the skin from this area 

 {el.c, fig. 118) shows the organ to be made up of multitudes of hexagonal 

 columns resembling the cells in honeycomb. Each column further consists of a 

 series of discs piled one upon another, ten to twelve of these being present in 

 each column. Each disc may be considered as having two surfaces, one ventral, 

 the other dorsal. The ventral surface bears a negative charge of electricity 

 while the dorsal is positively charged. 



The innervation of the electric organ will be considered in Chapter IX. 



