i8o Papers from the Marine Biological Laboratory at Tortugas. 



that is denser and somewhat more stainable than either of the others. 

 These granules are very numerous and fine at the periphery, where they 

 cause the outer part of the layer to stain deepest with eosin, and they lie 

 in the finer-meshed linom, and grow larger and fewer as one examines the 

 inner parts of the layer. They are of a slightly more refractive quality 

 than the linom and stain deeper with chromatic dyes the larger they get. 

 The largest also have some color of their own, a slight golden-brownish color, 

 somewhat like that of pigment granules. While the smallest granules seem 

 to lie in or attached to the strands of linom, the larger seem to lie in its 

 meshes in the hyalom. They remind the observer of the granules found in 

 certain other cells, particularly in the electric-motor cells of Torpedo, as 

 well as in other nerve-cells. In figure i6, plate 5, these finest granules are 

 seen in the outer part of the layer stained with eosin, while the inner part 

 does not show the larger ones that lie there. 



The larger granules are prone to gather about the nuclei and about the 

 inner part of the electric layer, as seen in figure 22, plate 8, where they took 

 the iron haematoxylin stain well. The larger, chromatic-staining granules 

 are also found, in groups or singly, in many parts of the fibrillar core. 

 While the larger ones found in the core, around the nuclei, and at the inner 

 edge of the cytoplasmic layer seem to stand in sharp contrast to the more 

 numerous and finer ones found in the outer part of the cytoplasm, one can 

 trace steps between the two kinds. 



The writer believes these granules to be the secreted or prepared nitro- 

 genous material used by katabolic processes to produce electricity, either 

 directly or indirectly. They must be, physiologically, the same granules 

 described by Ballowitz (5) in the cytoplasmic layer of the electroplax of 

 Raja, and by Schlichter (30) in the cytoplasmic regions on both surfaces of 

 the electroplax of Mormyrus. In this latter they were very large and not 

 easily demonstrated. The writer has seen some indication of them in 

 Astroscopus (12), but they would seem to be noticeably absent in other 

 forms, as Torpedo (although they have been figured here by Fritsch (20)), 

 and in Gymnotus (3) and Malopterurus (6), where such granules as Ballowitz 

 has described or figured would seem to be inadequate in size and number 

 for so heavy a duty. It will be noted in the above list that the weak- 

 electric fish seem to have these cytoplasmic granules best developed, while 

 the strong-electric fish show least of them. It is possible that these latter 

 possess them, or their equivalent, in a more fluid and less visible form. 



The cytoplasmic layer is marked off from the fibrillar core by a very 

 definite and sharp line. It can not be said that a definite membrane 

 exists here, although one may exist. The boundary between the outer 

 layer and the core is not an even or a straight one, but shows a wandering 

 course, especially at the two ends. At some points strands of the linom 

 seem to branch into the core (fig. 16, plate 5). At the anterior end in 

 particular it shows many extensive and complicated invaginations of its 

 granule-containing substance into the fibrillar core. Certain small portions 



