are probably exuded, outside the cell they are united to larger pieces 
of irregular shape. The granules are not only situated nearthe surface 
of the cell, but also occur in the mesial parts of the protoplasm; 
this can easily be seen by changing the level of the microscope. 
The relations of the substance of these yellow granules in 
the live-state of the cells, I have not sufficiently examined, neither 
am I in a position to say of what it consists. It is obviously this 
substance which gives the nervous system of Patella, as well as 
other Molluscs, the well-known yellowish coUour, and which Ra\YITZ, 
Haller, H. Schultze, Solbrig, Buchholz and others have de- 
scribed as pigment. I think it is most probable that the yellow 
colour is due to a substance, related to, or similar to hæmoglobin; 
the substance contains, probably, also fat, as the granules are deeply 
stained by osmic acid. Strange to say, I have, as a rule, not been 
able to observe quite similar granules in the sections of the cells. 
The reason why I do not exactly know, as my investigations are 
still too imperfect in this respect.') As also suggested by HALLER, 
I think it is very probable that this substance is principally engaged 
in the nutrition of the ganglion cells. I suppose that the correspond- 
ing substance in the ganglion cells of Homarus is the fatty substance, 
the existence of which we have above (vide p. io8) indicated. 
In the sections of some cells, I have observed a slight tendency 
to a differentiation of the protoplasm into darker and lighter stained 
parts (vide fig. 48). This tendency is, however, never very promi- 
nent. Generally, the protoplasm has a rather uniform, somewhat 
deep staining, which possibly indicates the extension of a (myeloid.^) 
substance, connected with the spongioplasm, through the whole 
protoplasm of the gangUon cells, as before mentioned in m}^ descrip- 
tion of the ganglion cells of Homarus, and possibly this substance 
is of the same nature as that which forms the granules (above 
mentioned) in macerated preparations. 
The processes of the ganglion cells. — The ganglion cells 
have a unipolar, bipolar or multipolar shape. Whether unipolar or 
multipolar, each cell has one nervous process only, passing into 
or through the central dotted substance, the other, protoplasmic 
processes, if they are present, are always very short, and have an 
appearance similar to the protoplasm of the cell. They are immedi- 
ately lost in the neuroglia-reticulation, or they pass to, and unite 
with the perineurium surrounding the central nervous system. 
^) Li a great many sections I have found a homogeneous yellow substance 
being extended in the protoplasm of the ganglion cells. It seems to be the same 
substance which forms the granules in isolated cells. 
