Central nervous system of Tunica nigra. 129 
erythrosin or eosin and methylen blue gave in varying degrees the 
appearance of tigroid-like material. In most cells, the deeply 
staining substance was concentrated into one part of the cytoplasm 
and not sub-divided into smaller masses; this was especially true 
of the central cells. In some of the more peripheral neurons the 
tigroid-like material was not so densely massed and appeared like 
flakes or dots, but there were few cells of this kind. In many 
neurons the whole cytoplasm was stained a uniform blue with no 
indication of darker masses. In cells of medium or large size there 
wa a large clear nucleus with a large spherical deeply staining 
Fig. L. Cells 
of various sorts from 
several ganglia of 
Tunica nigra. Fi- 
brillae are shown in 
two cortical cells, at 
the left in the figure. 
Tigroid-like mate- 
rial is shown in the 
larger cells (which 
are from the peri- 
phery) in the from 
of numerous evenly 
distributed, someti- 
mes concentrically 
arranged, masses or 
flakes ; in the smaller 
cells (which are from 
the center), as larger ; 
continuous patches. Some of these central cells show in a vacuole a paranuclear 
mass of yellowish pigment, indicated in the figures as a dotted area surrounded 
by a clear space. 900: 1. 
nucleolus. In some of the ganglia, there were numerous cells having 
vacuoles of various sizes, usually only one to a cell; these might 
be as large as, or even larger than, the nucleus. In a number of 
specimens these vacuoles were completely filled with a yellowish 
pigment, which seemed to be best preserved in formalin or FLEm- 
MING’S fluid, but often appeared partially dissolved out even in these 
fixatives; this gave the appearance of a large vacuole in the cell 
with a mass of light yellow substance in the center of the clear 
ärea (Fig. L). 
Mærcazr (1900) has shown similar “paranuclear” bodies in the 
nerve and gland cells in tunicates, which he says may be the same 
as the centrosome structures described in this group. Hunter (1898b) 
