xi ELECTRICAL FISHES 379 



and horizontally over each other (K batis), or are much bent 

 and undulating (E. circularis). In immediate contact 

 this is a stratum that is frequently drawn out into papilli- 

 form processes, similar in character to the nucleated zone which 

 invests the anterior surface of the entire plate, and forming the 

 posterior border of the plate ; this consists of a finely-granulated 

 mass of protoplasm richly set with nuclei. 



Eecent investigations of Fritsch (12 i) have contributed to 

 our knowledge of the structure and innervation of the Mormyrus 

 organ. Here, again, there are compartments of connective 

 tissue filled with gelatinous substance, and containing plates ; but 

 the finer structure seems to differ in many points. The nerve 

 enters by means of special prolongations of the plates, which are 

 club-shaped, and terminate in a conical, pointed form (" cones "), 

 which Fritsch compares with the expanded motor end-plate of 

 muscles. 



In Mormyridce, as in Torpedo, the fibres of the electrical 

 nerves (corresponding with the situation of the organ in the tail) 

 "are broad, unbranched axis -cylinder processes from large 

 ganglion-cells, which at given parts completely fill up the gray 

 matter of the spinal cord, and then leave the central organ as the 

 anterior roots. Fritsch makes the important observation that 

 the huge protoplasmic processes of these parent cells form a 

 number of short, broad anastomoses, so that the electrical ganglion - 

 cells, which form by actual continuity a narrowly circumscribed 

 complex, are, as it were, bound up by a common function. 

 Fritsch rightly lays stress on this observation, since on the one 

 hand it shows the undoubtedly nervous character of these proto- 

 plasmic processes, while on the other it indicates the possibility, 

 and, indeed, probability, of a similar course for the finest arborisa- 

 tions of motor nerve cells of the spinal cord in other vertebrates. 



Even from a more anatomical investigation of these " pseudo- 

 electric organs," it cannot be doubted that they are homologous 

 with striated muscles, and formed by the gradual transformation 

 of the latter. A glance at the tail of Mormyrus cyprino'ides, 

 when skinned, will reveal this, even to an unpractised eye. At a 

 certain point, i.e. near the end of the anal fin, the regularly- 

 arranged and flattened tendons of the caudal muscles suddenly 

 lose their solid, fleshy attachment, as described by Fritsch, and 

 stretch superficially across a transparent gelatinous mass, the 



