STUDIES ON THE NERVOUS SYSTEM OF CRUSTACEA. Al 
wards and break up into tufts of fibres near the ventral surface. 
The original fibre continues its course to a point a little beyond 
the centre of the dorsal surface of the ganglion, where it 
bifurcates, one branch turning upwards and curving outwards 
to the posterior root of Th. 111 (figs. 4 and 5, a), whilst the 
second branch continues in a transverse direction for some 
distance, and then turns suddenly forwards and runs into the 
neuropile of Th. 111 (figs. 4 and 5,6). Its fate here is a little 
uncertain, but it often presents an appearance which suggests 
that it ends in a tuft of fine branches, as in fig. 4, b. (on the 
right hand side of the figure). It should be mentioned that 
there is one difficulty in regarding the portion represented in 
fig. 5 asa single element, namely, that two central branches 
(c) are stained, whereas there appear to be only two when the 
complete system (fig. 4) is stained. 
Returning to fig. 4, it will be seen that the whole system 
there represented contains, in the first place, two elements 
similar to that in fig. 5, and lying upon opposite sides of the 
ganglion. In addition to this pair of elements, there is a fibre 
upon each side (fig. 4, d.), which appears to start from the 
point where the transverse fibre turns forwards to form the 
branch 6. This fibre (d) runs backwards for a short distance 
and then turns outwards to the posterior root of Th.1v. It is, 
however, probably not simply a branch of the element already 
described, but has a transverse portion of its own running 
parallel and close to the transverse portion of that element. 
In some preparations it is clear that the main transverse fibre 
of the whole system is of a composite nature. This is indicated 
on the right-hand side of fig. 4. 
A third fibre belonging to the system (fig. 4, e) appears to 
spring from near the centre of the transverse fibre, to curve 
forwards, and finally to pass out at the posterior nerve-root of 
Th. 111. It seems to be impossible to determine from embryos 
whether the fibres d and e are independent elements whose 
cells have never stained, or merely branches of the other 
elements of the system. It is to be hoped that the study of 
young adults may throw light upon this point, 
