No. 2.] COMPARATIVE CYTOLOGICAL STUDIES. 
case (Fig. 41) I found three nucleoli of approximately equal 
dimensions and homogeneous ; usually they vary somewhat in 
size and contain vacuoles. The shape of the nucleoli is either 
spherical or oval, or it may be irregular; certain ones stain 
scarcely at all, and appear granular : these might represent 
cases of degeneration. 
Smallest ganglion cells (Fig. 36). —Here a single nucleolus 
is the rule, though two may occasionally be found. They are 
spherical or oval, and vary considerably in size. Vacuoles do 
not seem to occur in them, though they might well escape 
observation from the small dimensions of the nucleoli, which 
often renders it difficult to distinguish the nucleoli from the 
larger chromatin granules. 
In all these ganglion cells the chromatin appears in the form 
of small granules, but on a preparation fixed with Hermann’s 
fluid and stained with Lyons blue (Fig. 45) it appeared as a 
network ; in this preparation the granules seemed to be united 
by fine fibers, which stained less intensely than the granules. 
But even here the connecting threads might consist rather 
of linin than of chromatin, since the solution of Lyons blue 
employed by me stained all the nuclear substances except the 
nuclear sap (paralinin). Such fibers often appear to radiate 
outwards from the surface of the nucleoli, as if the latter were 
suspended by them. The nucleoli always stain differently from 
the chromatin. 
There is, as a rule, a relatively small amount of nucleolar sub¬ 
stance in the cells of the second and third types in comparison 
with most of the other nuclei which I have examined ; but the 
nuclei of those of the first type, on the contrary, usually contain 
a relatively large amount of this substance, for not only may 
one or two of the nucleoli in a nucleus be quite large, but also 
a considerable number of nucleoli are frequently present. 
13. Ganglion Cells of Montagua fiilata (Verr.). 
(Plate 22 , Figs. 90 - 97 .) 
(The same types of cells may be roughly distinguished as in 
Do to.) 
