468 THE NERVOUS SYSTEM. 
3. The Oculo-Olfactory Bundle (Pl. XXIX., Fig. 2) passes 
outwards and backwards to the thalamon. It was first described 
by Viallanes. 
4. The Glosso-Olfactory Bundle descends to the infra-ceso- 
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 
Fic. 60.—A section of the Olfactory (antennal) Ganglion, seen with a jy 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 nerve; 
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 
