230 Papers from the Department of Marine Biology. 
by some fixatives. Thus many substances that are fixed and retained 
by osmic acid, formaldehyde, alcohol, and chromic acid are either 
dissolved or lost as an unchanged solution when the cell is fixed in pure 
sublimate, picric acid, or in Perenyi’s fluid. 
Thus when we find an important element, the ‘‘paranucleolus,” 
present in Tetronarce that is not to be distinguished so far in Torpedo, 
and when we find another element the“ telonucleolus”’ in Torpedo which 
has not been seen in Tetronarce, I believe that both of these elements 
must be present as a functional material in some form in both of 
these fishes. The cells are genetically closely related, they are used 
for the same identical purpose, and are both adult and in normal con- 
dition, and the apparently missing element in each case must be present 
in some form, possibly asa solution. For this reason the names applied 
in the present paper do not seem entirely satisfactory to the writer, in 
that they do not express the actual functions and chemical constitu- 
tions of the cell organs of the nucleus. Nor do all of these names 
permit of satisfactory comparisons being drawn between the nucleoli 
to which they are applied and to other nucleoli in other cells. It is 
certain that in this large nerve-cell we have a very high degree of 
differentiation of the nuclear organs and, apparently, an opportunity 
to make more exact studies of their identity and function than in any 
other cell, unless perhaps the egg-cell. And even in this respect the 
highly differentiated somatic cell such as that under consideration must 
be carefully studied and its elements traced back to the egg-cell before 
any general conclusions can be drawn about the meaning of the elements 
and their various activities in the nerve-cell. 
LITERATURE. 
The normal cell having been carefully studied, particularly as to its 
nucleus, the literature on the orientation of the nucleolus in Torpedo 
and experiments made on cells of Torpedo marmorata and Torpedo 
ocellata was next looked up to find any observations and experiments 
as to the question of a polarity of its nuclear contents. Such work had 
been done, mostly by Italian observers, and in particular by Professor 
Magini of Rome, who first observed a partial polarity of the entire 
nerve-cell in this fish (24). He examined many specimens of torpedoes 
at Naples and found that when the animal was killed by a violent 
death, as cutting by knife (vivisezione), the plasmosome was always 
found lying against that side of the nuclear wall which was nearest the 
axone. He believed at the time that the axone always left the cells 
in a ventral direction, and that this was therefore always an orientation 
in the direction of the axone when it was a ventral orientation. 
He found further that the entire nucleus was moved slightly in this 
same direction through the cytoplasm of the cell and that in conse- 
quence a crescentic space was left on the side of the nucleus opposite to 
