ANATOMY OF THE NERVE CENTRES. 465 



manner as the trabeculse, and in the section from which Fig. i, 

 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 trabeculse 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 (PI. 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-oesophageal Nerve Centres. The medullary white sub- 

 stance of the infra-o2sophageal 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-resophageal 

 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 



312 



