222 Papers from the Department of Marine Biology. 
tiation of the nuclear mass into at least six or perhaps seven distinguish- 
able nuclear organs, as well as the large size of the nucleus, makes it an 
exceptionally favorable subject for study. While some of these struc- 
tures are easily recognized as the same organs found in other nerve-cells, 
others can not as yet be so homologized and consequently their names 
may have to be changed when their real function becomes known by 
further study. The accompanying pen outline (text-figure 3) will serve 
to indicate the structures, with the names more or less temporarily 
applied to them. A more accurate drawing of the nucleus of this cell 
appears in figure 2, plate 1, as well as in figures 4 to 9, plate 2. 
The contents of this nuclear membrane are at least six in number and 
will be considered in the normal cell in the following order: (1) nuclear 
fluid; (2) nuclear achromatin or linin; (3) plasmosome or chief nucle- 
olus; (4) chromatin bodies or karyosomes; (5) a more or less frequent 
and unknown body of nucleolar appearance which I shall call tempo- 
rarily the telonucleolus; (6) the chromatin or perichromatin of Magini, 
a body which appears to be very closely connected with the chromatin 
nucleoli and contains a larger number of smaller bodies; (7) the peri- 
chromosomes, which are scattered through it in a regular order. The 
paranucleolus found in the nucleus of this cell in Tetronarce will not 
be described here, as it is not present in J'orpedo. 
The nuclear fluid can be dismissed with but short discussion. It is 
a questionable factor as an independent unit in the nuclear structure 
of this cell, and such of it as is not combined with the other elements of 
the nucleus must be looked upon as a non-vital element. This nucleus 
was put under the cell-dissecting arrangement of Barber and torn to 
bits with the glass needles. Under this treatment it was found that 
the nuclear membrane could be punctured or torn or even removed 
altogether and that the mass of the nucleus remaining was of jelly-like 
rather than of fluid consistency. This seems to show the absence of 
any large quantity of free liquid material during life. On the other 
hand, some of the best Flemming fixations, when the largest amount of 
nuclear material was fixed and retained, still showed some fine empty 
spaces, while in all other fixations much larger empty spaces are present 
in the nuclei, and these spaces must represent either shrinkage or 
fluids which have dissolved out. The evidence seems to show that 
both are true; that some little free and uncombined fluid is present in 
the nucleus and that this occupies very small spaces that are more or 
less enlarged by shrinkage of the remaining structures in the process 
of fixation. 
The viscous, weak-staining, non-chromatic substance or linin of the 
nucleus will next be considered. This is probably a nucleo-albumen 
and is of a jelly-like consistency in the live cell. As may be seen in 
figure 3, plate 2, it is scarcely visible during life, although dark-stage 
oblique illumination would probably show it more plainly. In the 
