46 EDGAR J. ALLEN. 
cesophagus, and they probably therefore enter the brain. The 
fact that two pairs of elements in Abd. vi send fibres to the 
brain, whilst only one pair has been found in the other abdominal 
ganglia is in accordance with the known composite nature of 
this ganglion. 
PropasLe Moror Evements.—Of elements consisting of a 
cell in a ganglion and a fibre passing out of the cord by one 
of the nerve-roots, two principal kinds have been found in 
the abdomen, as in the thorax, namely (1) those in which the 
fibre passes out through one of the roots of the ganglion in 
which the cell lies, the whole of the element within the central 
nervous system being confined to one ganglion; and (2) those 
in which the fibre passes out through a nerve-root of some 
ganglion other than that in which the cell lies. 
These elements are represented in figs. 2and 3; fig. 2 giving 
the appearance presented when the elements upon both sides 
of a ganglion are stained ; fig. 3, that when they are stained 
upon one side only, and indicating therefore the course of the 
individual elements. Each of the elements to be described 
has been found in all the ganglia from Abd. 1 to Abd. v. 
ELEMENTS CONFINED TO ONE GaNnGLION.—The element a, 
shown in figs. 2 and 3, takes its origin in a cell, which lies 
near the centre of the ganglion and at its ventral surface. 
The fibre passes first upwards and outwards, turns inwards, 
and after a short course divides into two branches, one of which 
passes out of the ganglion by the posterior nerve-roots, whilst 
the other runs across to the opposite side, keeping close to the 
corresponding branch from the element of that side (fig. 2) 
and subsequently breaks up on the opposite side of the gang- 
lion. The fibre gives off numerous fine branches during its 
course through the ganglion, which have not been represented 
in the somewhat diagrammatic figs. 2 and 3, but which may 
be seen in fig. 8, drawn from a preparation fixed with am- 
monium picrate (fig. 8, a; Abd. 1 and 111). 
Element 6 (figs. 2, 3 and 8) is similar in most respects to 
