GANGLION-GLOBULES. 153 
a protecting investment of fibres resembling areolar tissue to 
both structures. This is certainly a very striking comparison, 
but the external investment must not in either instance be re- 
garded as a something wnessential, as a structure composed of 
other elementary parts, for the ganglion-globules, like the yelk, 
are true cells, and their external covering is an essential com- 
ponent part of them; it is the cell-membrane. The vitelline 
membrane of the bird’s egg, while contained in the ovary, 
is perfectly structureless, not composed of more minute ele- 
mentary parts ; the same is the case with the investment of the 
ganglion-globules. They are both of them true simple cells. 
The parenchyma of the ganglion-globules forms the cell-con- 
tents, and the vesicle in their interior is the cell-nucleus; the 
small corpuscles which it contains are the nucleoli. The vesicle 
of the ganglion-globules lies, as in other cells, eccentrically 
upon the internal surface of the cell-membrane. ‘This cell- 
membrane may be most distinctly observed in the ganglion- 
globules of the sympathetic nerves of the frog, previous to their 
junction with the sacral plexus. (See pl. LV, fig. 10, a.) It there 
appears comparatively dark, and sharply defined, both externally 
and internally, so that its thickness may be readily measured. 
Valentin has already remarked, that the capsule of the gan- 
glon-globules is thicker in the lower animals. In the situation 
before mentioned in the frog, it seems as though a ganglion- 
globule were sometimes formed within another cell. (See fig. 
10, 4.) The ordinary contents of these ganglion-globules is a 
minutely-granulous, yellowish substance. On one occasion, 
however, I saw a ganglion-globule from the head of an ox (I 
do not precisely know from what part it was taken), in which 
the granulous appearance was confined to the surface, the inte- 
rior being clear,—a fact which was rendered distinctly percepti- 
ble by causing the globule to roll about. It is nothing remarkable 
that two nuclei should sometimes occur in one ganglion-glo- 
bule ; we have observed this already in several cells, im those 
_of cartilage for instance. In those instances, however, only 
one of them was the true cell-nucleus, the cytoblast of the car- 
tilage-cell, the other being a subsequent formation within the 
cell. 
