4,72 EDGAR J. ALLEN. 
sented in blue in fig. 4, and are also seen in fig. 8, which is 
drawn from a fixed preparation. This latter figure illustrates 
the extent to which the systems C and D will stain in a favour- 
able preparation. The elements can be recognised in six seg- 
ments, although in some cases the cell has not stained. The 
cells of elements D lie in the posterior portion of the lateral 
ganglionic mass. The fibre passes forwards and inwards through 
the neuropile, giving off numerous arborescent branches to the 
latter. On entering the next ganglion in front, the fibre has 
reached the outer border of the median ganglionic mass, and 
after giving off a little tuft of branches immediately in front 
of the tuft in which one of the elements C ends, it pursues a 
direct anterior course, ending in a tuft of branches in the 
ganglion next but one to that in which it started. This 
terminal tuft lies opposite the terminal tuft of one of the C 
(ried) elements, and immediately behind the lateral tuft of the 
D (blue) element of the next ganglion. These relations will, 
I think, be more readily understood from a study of fig. 4 than 
by any further description. It should, however, be stated that 
the three tufts standing opposite each other are at exactly the 
same level in the cord, being all three in the focus of the micro- 
scope at the same time. The fine fibres of which they are 
composed are often obscured owing to the rapidity with which 
they assume the beaded condition. 
Il. Motor ELements. 
Under this head will be described those elements which 
consist of a cell in the ganglionic cord, giving off a fibre 
which, after sending arborescent branches to the neuropile, 
passes out from the cord by one of the nerve-roots. Many of 
these elements (not improbably all of them) are motor, and in 
some cases I have been able to trace the fibre from the cell, 
through its whole course, until it breaks up on a muscle. 
Such a case is represented in fig. 9, which was drawn from a 
preparation preserved in ammonium picrate.! 
1 The slight break in the fibre, which was not present when the prepara- 
tion was fresh, is, even on an examination of the preserved preparation, due to 
