HISTOLOGY 



facing directly forward and backward. The anterior face is smooth and 

 is the nutritive surface. The posterior or electric surface is regular and 

 sends out a number (few compared to those of Gymnotus] of evaginated 

 processes that are long and usually curved. The electric nerve applies 

 its curious, heavy mass of endings to these processes, and in the ordi- 

 nary preparations one 

 has difficulty to say 

 when the nerve ends 

 and the process begins. 

 The nuclei are 

 fairly numerous 

 throughout the cyto- 

 plasm and are large 

 and clear. The elec- 

 tric rods, as in Gym- 

 notus, are found in 

 all surfaces, even those 

 of the processes, and 

 they are longer and 

 sharper than in that 

 form. In some prepa- 

 rations the elect ro- 

 chondria are very 

 clearly seen and are 

 large granules resting 

 among the rods (Fig. 

 in). 



The most peculiar 

 feature of this electro- 

 plax is the fact that it 

 contains, as a middle 

 bundles, which run in 

 These are each corn- 



FIG. in. Portion of an electroplax from Mormyrus. el.s., elec- 

 tric surface from which part of a papilla projects; mus.f., 

 muscle fibers in middle layer of electroplax. Electric rods 

 shown on both surfaces. (After SCHNEIDER.) 



layer, a series of small but perfect muscle 



several directions in the plane of the electroplax. 



posed of a number of real myo-fibrils fully striated, but in a somewhat 



different pattern from the striation of the regular body muscle. 



In this form again we have the same two indications of a multicellular 

 origin of the electroplax. Besides, and added to these, is the presence 

 of the myo- fibril bundles, each of which would seem to represent the 

 functionless remains of one of the constituent fibers that helped form the 

 plate. 



The last of these teleost forms of electric tissue is found in the fish, 

 Astroscopus, which has developed what appears to have been part of 

 an eye-muscle into its electric organ. This tissue is again composed 



