1 88 Papers from the Marine Biological Laboratory at Tortugas. 



In doing this it has formed a much more intimate connection than may 

 be seen in other places where the nerve-fibers touch the electroplax very 

 closely, even being partly embedded in it, or running through the fundus 

 that lies between two papillae, where the fiber is closely pressed on three 

 sides by the surface of the electroplax. In these fiber contacts the con- 

 nective-tissue sheath persists, while in the club-shaped or heavily rounded 

 endings the connective-tissue sheath is lost, lefc at the surface, and the 

 little protoplasmic bridges, shown when slight shrinkage has taken place, 

 testify to the intimacy of the contact. In addition a slight amount of fine, 

 golden-colored granules surrounds the nerve-ending, lying on its surface, 

 between it and the substance of the electroplax (figs. 24 and 25, plate 9). 

 These granules are not found on any other part of the nerve surface. 



Naturally the paper of Schlichter (30) was carefully examined to see 

 what he had found as to the ending of the electric nerves on the related form, 

 Mormyrus oxyrhynchus. He had adult material, but otherwise was no 

 better off than the writer in the possession of material which had been 

 treated especially for neurological study. He describes the nerve-fibers with 

 their medullary sheaths as coming in contact with the large process of the 

 electroplax and then suddenly ending just as they reach certain large inden- 

 tations of the surface of this electroplax. He found in these indentations 

 only a little coagulated material and some nuclei. 



The writer has no doubt that the slight coagulum represents what 

 remains of a club-shaped nerve-ending similar to that which he finds in 

 Gymnarchus. The nuclei, from their position in Schlichter's picture, are 

 evidently the nuclei of terminal connective- tissue coverings. If this idea 

 be correct we will have a very simple but interesting form of nerve-ending, 

 much larger in size than that found on any muscle or any other electric 

 organ and one in which it will be, apparently, easier to study the intimate 

 contact of nerve-substance with motor-substance from a cytological point 

 of view than in any other form. In particular, we should try to stain these 

 endings with the nitrate of silver and methylene blue methods devised for 

 neuro-cytological studies. This work, however, can be undertaken only 

 on the ground, with good laboratory facilities and with an abundance of 

 fresh material. 



The writer has published observations on some peculiar horizontal, 

 pointed rods, or pointed threads, found imbedded in the electric layer of 

 the electroplax of Astroscopns. At that time he suggested that they might 

 be in some way homologous with or related to the "Stabchen" because of 

 the absence of any other well-defined "Stabchen" in this fish. Such 

 structures are not found in the present Gymnarchus larva, but they have 

 been seen and described in Raja, in a paper soon to be published. Their 

 presence in Raja, in addition to the "Stabchen," proves them to be entirely 

 different cell organs. 



One word in regard to certain possibilities for the physiological study 

 of the electric organ in Gymnarchus. A recent paper by Bernstein and 



