Structure and Polarity of Electric Motor Nerve-Cell in Torpedoes. 255 

 EXPLANATION OF PLATES. 



All figures represent parts or the whole of electric motor nerve-cells from either Torpedo 

 marmorata or Torpedo ocellata, which the writer believes to interbreed and to be structurally 

 the same. 



Magnifications are not given, because absolute measurements of the average cell are given 

 in the text-. 



Where the results of experiments are shown the natural direction of gravity and the 

 natural direction of the electric current are indicated by an arrow with one barb, while the 

 applied centrifugal force and the applied experimental current are indicated by an arrow 

 with two barbs. 



PLATE 1. 



FIG. 1. A normal cell from Torpedo marmorata, No. 16. Fixed in Bouin's fluid to which 

 5 per cent potassium bichromate was added. Ironhematoxylin. Shows large and numerous 

 spindle-shaped chromophyllic bodies; also smaller, round, and deeper-stained neurosomes 

 situated between chromophyllic bodies. One large and one small plasmosome. No telo- 

 nucleolus. Typical chromatin bodies. 



FIG. 2. A normal cell from Torpedo ocellata, No. 1. Bouin fixation. Cut in celloidin after 

 bulk-staining with borax carmine and hemalum. One large and one small plasmosome. 

 The small plasmosome lies inside of a telonucleolus. Several elongate and darker-staining 

 nerve-sheath nuclei outside of cell; also three larger, rounder, and lighter-staining neuroglia- 

 cell nuclei. 



PLATE 2. 



FIG. 3. A living cell from Torpedo marmorata, No. 16, seen with 2 mm. apochromatic 

 objective, under very slight pressure of cover-glass and with iris diaphragm well cut down 

 to bring out refractive properties of cell-structures. Plasmosome, karyosomes, nuclear 

 membrane, and neurosomes sharply brought out. Perichromosornes slightly brought out, 

 and cytoplasm granules around nuclear membrane weakly brought out. Some trace of 

 chromophyllic bodies to be seen; also of neurofibrils. 



FIGS. 4, 5, 6, 7, 8, and 9, nuclei from cells of several torpedoes, to show different arrange- 

 ments of plasmosomes and of telonucleolus when present. 



PLATE 3. 



FIGS. 10 to 18. A series of cells from Torpedo marmorata, No. 16. Macerated for 3 hours 

 in one-third alcohol and teased in very weak glycerin on slide. Distribution and color of 

 neurosomes well shown. Form of individual neurosomes not well shown, as only masses 

 of them appear. The functional polarity of the cell well known. Dendrites tend to gather 

 at one end or pole and neurite with heaviest masses of neurosomes at the other. Cells do 

 not lie in natural relative positions in plate, as selected specimens were drawn from different 

 slides. 



PLATE 4. 



FIG. 19. Two cells from a section of the electric lobe of Torpedo ocellata, No. 3, through 

 which a current was run from left (anode) to right (kathode). These cells show the general 

 pressure on the entire nucleus in the kathodal direction, which appears to result in the 

 appearance of the semilunar space on the anodal side. The other changes as described in 

 the text. 



FIG. 20. A single cell from the electric lobe of Torpedo ocellata, No. 5, to which a very 

 strong current has been applied for 30 seconds from left (anode) to right (kathode). Fixed 

 in sublimate, stained in iron hematoxylin. Shows increased results over preceding experi- 

 ments. For description see text. 



PLATE 5. 



FIG. 21. A cell from Torpedo ocellata, No. 3, that has been subjected to a centrifugal force 

 of 543 times gravity for one minute. Nucleus somewhat compressed and an equatorial 

 canal formed. Plasmosomes alone moved by the force. Bouin fixation. 



FIG. 22. A cell from Torpedo ocellata, No. 20, which has been subjected to a force of 601 

 times gravity for about half an hour and in a ventro-dorsal direction. Both plasmosome 



