124 
Psyche 
[December 
three abdominal ganglia of the larva. This ganglionic mass 
is roughly rectangular in shape (figs. 1 & 2), and is con- 
stricted near the middle (anterior-posterior aspect). The 
anterior portion, more conveniently termed the anterior lobe, 
is composed of the two larval thoracic ganglia (Th. II & III), 
whereas the posterior lobe is composed of the first three 
larval abdominal ganglia (Abd. I, II, III). These lobes are 
identified by a prominent tracheal tube (figs. 1 & 2 Tr.) 
which passes dorsad between them from the ventral surface 
of the ganglia in a median (dextro-sinistral) position. They 
are further differentiated by a noticeable constriction in the 
neuropile. (In these figures the neuropile is white and the 
ganglionic cell layer stippled. For the sake of clarity fiber 
tracts are shown as single fibers.) 
In sagittal view (fig. 2) there are five bundles or tracts of 
fibers which enter the anterior lobe of the ganglia from the 
pro-mesothoracic commissures (c). The uppermost bundle 
(fig. 2 p) consists of motor association fibers originating in 
the prothoracic ganglion and extending to the posterior lobe 
of these fused ganglia. Fibers are given off from this bundle 
and ramify among the fibers of the neuropile of both lobes. 
Below this bundle there is a large fibre tract (fig. 2, q) which 
passes through the entire length of the ganglionic mass ; side 
branches are given off which extend into the neuropile of 
each lobe. These are motor fibers originating in the brain 
and extending through the ganglionic mass. 
The middle bundle of fibers (b) is quite large and ends in 
the neuropile of the anterior lobe. These are sensory fibers 
which come directly from the wings. It is quite surprising 
to find such a large bundle of nerve fibres which can be traced 
directly into the wings themselves, but this is more readily 
comprehended when one considers the large number of ol- 
factory pores found on the wings of Lepidoptera by Mclndoo 
(1917). In Ephestia this bundle leaves the pro-mesotho- 
racic commissure (c) at a point just posterior to the pro- 
thoracic ganglion. 
The fourth bundle of fibers (fig. 2 r) is comparable to the 
second in that it extends throughout the entire mass of fused 
ganglia passing toward the abdominal ganglia. It originates 
in the region of the brain and is composed of sensory fibers ; 
side branches are given off to the neuropile of both lobes. 
