Structure and Polarity of Electric Motor Nerve-Cell in Torpedoes. 219 



found to be lacking in the extreme periphery of this and other nerve- 

 cells, where its absence has been accounted for in various ways by 

 Rhode (30) and other writers. As this substance is also of no signifi- 

 cance in regard to any polarity or orientation of the cell, it will not 

 be dealt with further in regard to its properties or meaning and its 

 literature will not be cited. It may be seen in a well-stained condition 

 in figure 1, plate 1. 



Another content of the cell was of more importance as a guide to 

 polarity. This consisted of a number of granules of a substance first 

 described by M. Shultze and subsequently more definitely by Garten 

 (17 B). These granules were best studied by the writer in the living 

 cell and then in macerated and teased specimens and lastly in sections. 

 Their most prominent feature is only shown when studied in the living 

 cell. Here they show a very high index of refraction, which disappears 

 when treated with the usual clearing reagents. Thus these granules 

 do not appear in unstained sections on account of their refractive 

 properties. As Garten says: "am ungefarbten Preparat waren die 

 Kornchen nicht sichtbar." 



In fresh or recently fixed formalin material these granules were visible 

 not only by reason of their refraction quality but also because of their 

 color. This was much more noticeable in some cases than in others 

 and in one case their color was a rich, golden-orange, like some of the 

 lighter brown pigments found in vertebrate skin and elsewhere. The 

 depth of color in the granules was found to correspond to the external 

 and internal color of the electric lobes of the brain in which they are 

 found and in Torpedo ocellata and Torpedo marmorata this varied from 

 a faint yellowish tinge in fully 50 per cent of the specimens to the rich 

 orange found in one or two examples as mentioned above. It thus 

 would seem that in certain specimens this substance gives the lobes 

 their peculiar color, but that whether colored or not the same granules 

 exist in all specimens. The electric lobes of the large American 

 torpedo, Tetronarce occidentalis, are but little different from the rest 

 of the brain in color and it will probably be found that in this form the 

 refractive granules are present but colorless. In Narcine braziliensis, 

 the little torpedo of South America and the West Indies, the electric 

 lobes are a very deep and brilliant orange in color, caused undoubtedly 

 by the coloration of these same granular structures in all specimens. 



In size these granules were variable and usually less than a micro- 

 millimeter in diameter. Some might have attained to this size, 

 Garten speaks of them as round, but in the fresh cells many of them 

 seemed irregular in shape and decidedly angular and elongate. In 

 fixed and stained sections (plate 1, fig. 1) they appear round. 



The fixation and staining of these granules seems difficult, and best 

 results were attained by a quick, hard fixation with pure sublimate or 

 Bouin's fluid and a rapid embedding. Figure 1 of plate 1 shows a case 



