ANATOMY OF THE NERVE CENTRES. 405 
manner as the trabecul, and in the section from which Fig. 1, 
Pl. XXX., is taken some of these fibres are seen to form a dis- 
tinct commissure between the two tubercles of opposite sides. 
The anterior tubercle is apparently connected with the gray 
matter overlying the frontal lobe, its fibres forming a rudi- 
mentary calix similar to, but much less developed than, those of 
the corpora fungiformia. 
The idea that the trabecule and their tubercles are discon- 
nected with the rest of the brain is quite inconsistent with what 
we know of the definite nervous tracts of brains generally. 
The trabeculae and peduncles of the corpora fungiformia 
receive distinct fasciculi of fibres from the crura and the antennal 
ganglia (Pl. XXIX., Fig. 2). The latter decussate in the middle 
line. Beside these connections, numerous strands of fibres 
pass out of the trabecular system into the mesocerebron and 
corpus centrale. Hence it will be seen the corpora fungiformia 
have extensive and definite bundles of fibres connecting them 
with almost every part of the central nervous system. 
The principal inter-ganglionic tracts are described in relation 
to the parts which they connect with each other; the most 
important are the peduncles of the antennal ganglia, the optic 
peduncles, and the peduncles of the procerebral lobes, the oculo- 
olfactory tracts and Bellonci’s bundles. 
The Infra-esophageal Nerve Centres—The medullary white sub- 
stance of the infra-cesophageal ganglia consists almost entirely 
of interlacing fibres ; longitudinal fibres, derived from the crura 
and cephalo-thoracic cord, which they unite with each other ; 
transverse fibres, which arise in the gray cortex of the centre 
and, after decussating in the middle line, ascend in the opposite 
crus; and fibres connected with the roots of the maxillary 
nerve. 
The anterior portion of the medulla of the infra-cesophageal 
‘centre is distinctly separated from the rest, and forms two dis- 
tinct fasciculi, separated from each other by a median furrow. 
These two bundles of fibres are pierced by the deep root of the 
maxillary nerve, and exhibit a distinct median decussation. 
‘Some, at least, of the decussating fibres are readily traced to 
31—2 
