ANATOMY OF THE NERVE CENTRES. 461 



pharyngeal, maxillary and antennal nerves. The pyramidal 

 ganglion consists of large cells closely packed together, and 

 there are several gigantic nerve cells in the gray matter sur- 

 rounding the oesophagus, resembling the largest stellate cells 

 of the anterior cornua of the spinal cord of Vertebrates. 



The Corpora Funglformia are two in number, on each side of 

 the brain, an external and an internal corpus fungiforme. These 

 bodies may be described as cup-shaped prolongations of the 

 medulla, filled by and imbedded in the cellular cortex on the 

 posterior surface of the brain. 



Each corpus fungiforme is said to consist of a calix, filled by 

 and covered with small nerve cells. 



Each calix is funnel-shaped, supported by a stalk or peduncle 

 at its narrow extremity. The peduncles of the internal and 

 external calix perforate the medullary core, or hemisphere of the 

 mesocerebron, and unite with each other, forming a thick bundle 

 of parallel fibres ; this bundle is termed the trabecula. The 

 trabecula crosses the internal cavity to the anterior surface of 

 the brain, and terminates in a rounded caput in the lower part of 

 the frontal lobe. From the caput two short thick processes are 

 given off at right angles to each other, one ascends through 

 the frontal lobe, the anterior tubercle ; the other takes a nearly 

 horizontal course to the medium line, the internal tubercle. In 

 the Orthoptera the trabeculse are far more massive than in the 

 Diptera or Hymenoptera (compare Fig. 54). 



The Calices. Each calix is a hollow cone of very fine fibres, 

 which radiate from the apex of the cone, where they form the 

 peduncle of the corpus fungiforme (Hinterast, Flogel; Pilzstiel, 

 Dietl) ; these fibres extend from the calix into the gray sub- 

 stance ; and the small round cells of the cortex are frequently 

 seen in sections, arranged in radial lines corresponding to the 

 course of these fine fibres (PL XXXIII. , Fig. 2). The calix 

 itself is formed by the union of these fibres in their course to 

 the trabecula. It is not circular in transverse sections, but is 

 seen to be corrugated irregularly in a longitudinal direction. 



Historical and Comparative Anatomy of the Corpora fungiformia. 

 Dujardin first discovered the Calices in Bees (Apis and 



