220 Papers from the Department of Marine Biology. 



where Bouin's fixative containing 5 per cent potassium bichromate 

 followed by a hard stain in iron hematoxylin has brought them out 

 black. In every case where the decolorization was carried far enough 

 to show the chromatin nucleoli the bodies in question were decolorized 

 and could not be made out by the best lenses and refraction conditions. 

 The alcohols took out any brown or yellow color that they possessed. 

 I shall follow Held and Garten in calling them neurosomes. 



These neurosomes were found scattered all through the cell-body 

 (cytoplasm) and appeared to lie in much more intimate relation to the 

 fibrillar substance than the Nissl bodies did. Thus they appeared to 

 lie in spaces between the Nissl bodies. While scattered sparingly 

 through the whole cytoplasm, they were gathered in large masses at 

 the pole of the cell from which the axis-cylinder took its origin. Here 

 they formed a thick ring around the axis-cylinder process and are to 

 be seen in figures 10 to 18, plate 3, where 9 cells from two torpedoes are 

 shown after bits of the electric lobes had been macerated and teased 

 out on the slide. In this case the neurosomes were a rich golden brown. 



In figure 3, plate 2, a cell is shown as it appeared in the living state 

 under closed substage diaphragm, thus showing the parts of the cyto- 

 plasm by diffraction. The neurosomes can be very easily seen under 

 this condition apart from any color that they may or may not possess. 

 The neurosomes are also shown by the strongest osmic-acid fixations, 

 but are not a fat of the ordinary kind (see Dogiel, 12s). They are found 

 in other nerve-cells and can be best seen in living tissue, pressed between 

 the thin cover and a slide and examined with the highest powers and 

 with the small diaphragm. 



These "neurosomes" are the bodies that have often been described 

 by all writers on the structures of the nerve-cell as "pigment granules," 

 or collectively as the "pigment body." They have, perhaps, been 

 best studied in the spinal ganglion nerve-cells of vertebrates, especially 

 the mammals. Dogiel, in a review of the structures of these cells, 

 in a book of comparatively recent date (12 B), describes them and cites 

 a valuable list of writers on the subject who have discussed the struc- 

 tures from a physiological and chemical side. This summary, while 

 not giving the substance a definite name, or associating it with any 

 known function of the cell, does show the structures to be one and the 

 same with the structures described above by the present writer and, 

 further, clearly shows them to be a constant and specific organ of 

 practically all nerve-cells rather than the products of senile or patho- 

 logical nerve-cells. That they are closely associated with the func- 

 tional polarity of the cell, as a nerve-cell, is clear from their concentra- 

 tion near the origin of the efferent process, but that they are not in any 

 way concerned with the polarity of the nucleus under discussion is 

 equally clear, and they will not be further discussed in this connection. 



A slightly different and thin layer of homogeneous cytoplasm, the 

 perinuclear cytoplasm, is found around the nucleus. It is marked 



