PRENTISS, eurofibrillar Structures. 165 
nucleus; the others take a more peripheral course, a fact 
which is not in agreement with ApATuHy’s figures. In the same 
section another cell of the same type was found (Figure 2, 
Plate V). In this case, however, there are many fibrils of 
nearly equal size in the cell process, although the networks 
within the cell are incompietely stained. Neither in verte- 
brates nor in crustacea do the neurofibrillae of the nerve cells 
show any marked correlation in size and function. 
In the giant cells of the leech there is no inner network 
about the nucleus; the fibrillae are very numerous in the cell 
process and divide to form a network of small irregular meshes 
throughout the greater portion of the cell. A portion of such 
a cell is shown in Figure 4 (Plate V) and gives some idea of the 
great number of fibrillae which these giant cells contain. 
The fibrillar structures in the ganglion cells of Astacus 
and other decapod crustacea resemble somewhat those of the 
larger type of cells in Azrudo. Such structures have been 
described by BEeETHE (’98), and OwsIANNIKOW (: 00). BETHE 
describes the fibrillae within the ganglion cells of Carcinus as of 
nearly equal size, and forming a network of somewhat large 
meshes throughout the plasma of the cell. OwsIANNIKOW 
finds primitive fibrillae of two sizes in the nerve cells of 
Astacus ; the smaller of these are found about the nucleus in 
the form of a network; the larger fibrils occupy the peripheral 
portion of the cell, and are the continuations of the fibrillae in 
the cell process. 
My preparations of Astacus showed no trace of a network 
of fine fibrillae about the nucleus. The usual condition ob- 
served is seen in Figure 15 (Plate VI). The fibrillae appear 
relatively large and form a few large meshes in the peripheral 
region of the cell. This figure corresponds to the descriptions 
of BerHEe and resembles the only drawing which Owsranni- 
KOW gives of the neurofibrillae in the cells; the figures of the 
latter do not support the statements he makes in the text. 
Fibrillar Structures tn the Cell Processes. 
BETHE (’98) was the first to observe that in the crab a 
