Structure and Polarity of Electric Motor Nerve-Cell in Torpedoes. 249 



The general results were in a large measure like those found in the 

 preceding experiment (see fig. 23, plate 5). A careful comparison of 

 the two experiments will show such difference as came out. 



The plasmosome was evidently thrown down with greater force. 

 In many cases it dented the nuclear membrane. As in all other cases, 

 however, it was not in the exact center of the thrown-down mass, but 

 occupied one corner, the central corner, in a proportion of the cases 

 that corresponded fairly well with the percentage of orientation, 70 

 per cent. The shape of the plasmosome was in no way changed, except 

 in a few cases which might well have been caused by the fixative. 



More of a change than this appeared, however, in the chromatin 

 bodies. These structures had been flattened somewhat in most cases 

 and in some cases were much flattened. The flattening, in all cases, 

 was seen only in the perichromosomes and no signs of such a condition 

 were visible in the karyosomes. These objects had not only retained 

 their shape, but were also always in the center of the flattened chroma- 

 tin bodies, as being in this case the center of an oval instead of a circular 

 mass. It was also true that the mass of perichromatin was in most 

 instances much smaller than in the control, and this appeared to be 

 due to a loss of some part of the material rather than to its compression. 

 However, the same phenomenon is often true in normal specimens, 

 where it appears to be a result of certain fixations. 



Another varying condition in this specimen, as well as in torpedo 

 No. 20, was seen in the achromatic portion of the nuclear content. 

 This material has usually been figured and described as a reticulum 

 of some kind with a more fluid material, the " nuclear sap," in its 

 meshes; and it does so appear in most of the nuclei of the motor 

 electric nerve-cells of Torpedo, as seen in mounted sections under the 

 microscope. The variation as noticed here consisted in the sizes of 

 the meshes of the reticulum. Some showed a coarse meshwork and 

 others a very fine one, with all intermediate sizes of mesh to be seen 

 in the specimen. This reticulum has been considered by many investi- 

 gators to be an artifact in part or in whole, and in particular the 

 researches of Kite and Chambers and others show that, in the living 

 cell, no such network of fine fibrils exists in reality. In the torpedo's 

 electric motor nerve-cell this reticulum is clearly shown to be an artificial 

 condition by the fact that with most of our standard fixations the outer 

 layers of cells in a mass of fixed tissue show a finer reticulum in the 

 nucleus, while the inner cells in the same bit of tissue show a coarser 

 pattern. 



This reticulum is not an alveolum, in that its various cavities break 

 into one another at frequent intervals. It is a real reticulum, but not 

 one composed of thin threads. Rather it appears to be such a reticulum 

 as would be formed if the dividing walls of an alveolum were to be 

 broken or punctured through at frequent intervals. Its varying pat- 



