468 



THE NERVOUS SYSTEM. 



3. The Oculo-Olfactory Bundle (PI. XXIX., Fig. 2) passes 

 outwards and backwards to the thalamon. It was first described 

 by Yiallanes. 



4. The Glosso-Olfactory Bundle descends to the infra-oeso- 

 phageal ganglion. 



The Medullary Substance of the antennal ganglion has a very 

 remarkable structure, exactly similar to that of the olfactory 

 lobe of a Vertebrate. This structure was described by Dietl 

 [175], and more recently by Bellonci [183], who terms it the 

 olfactory ganglion. 



In optical sections it appears to be composed of a number 

 of small lobes. These were formerly mistaken by Leydig for 



' ^ >^ - > 



' 



P 



KiL. 60. A section of the Olfactory (antennal) Ganglion, seen with a ,'., oil immer- 

 sion objective, showing the reticular glomeruli in which the fibres of the 

 antennal nerve (a) terminate and from the centres of which those of the olfactory 

 peduncle (/>) take their origin. 



giant cells. Each lobe appears in properly preserved sections 

 as a glomerulus of fine fibres ; the centre of each is connected 

 with a fasciculus of fibres from the peduncle of the ganglion ; 

 and the periphery is continuous with a reticular network of 

 fibres, which connects the glomerulus with the cells of the 

 cortical substance, and with the fibres of the antennal nervr : 

 these are, many of them, given off from the glomeruli, a small 

 fasciculus arising from each (Fig. 60). 



Both the glomeruli and the fibres of the antennal nerve 

 are deeply stained by osmic acid, whenever this reagent is 



