54 



ANTS. 



Kuckard (1875), '"'Hindi <<87<, IJiell 1187(11, Hogel 11878) and 

 Kenyon ( 1 890 ) . 1 cannot, however, omit consideration of two region.^ < > f 

 the ant brain, namely, the frontal and olfactory lobes, which have fre- 

 quently been compared with the cerebrum and olfactory lobes of verte- 

 brates. The frontal lobes contain two pairs of extraordinary structures, 

 the pedunculate, or mushroom bodies (Figs. 28-30, />/> i.each eonsisting 

 of a cup-shaped mass of nerve-fibers, the calyx, with a stem formed of 

 a stout bundle of similar fibers which run back into the mid-protocere- 

 brum. The calyces are embedded in a dense accumulation of minute, 

 deeply-staining ganglion cells, which form the bulk of the frontal lobes 

 and evidently give rise to the fibers of the calyces and their stems. 

 Each olfactory lobe consists of a central fibrous portion containing 

 peripherally a large number of round bodies of still denser fibrous struc- 

 ture and a cortical portion made up of larger ganglion cells. The round 

 bodies have been called glomeruli from their resemblance to the well- 

 known structures in the olfactory lobes of vertebrates. Since the 

 antenna? of ants are mainly organs of smell, the occurrence in the deuto- 

 cerebrum of structures so much like those in the olfactory organs of 

 vertebrates is not without interest. 



FIG. 28. Heads of worker (A), female (jB), and male (C), Lasins brevicornis, 

 drawn under same magnification, with brain, eyes and ocelli viewed as transparent 

 objects. (Original.) oc, Median ocellus ; pb, pedunculate bodies ; og. optic ganglion ; 

 on, optic nerve ; ol, olfactory lobe ; an, antennary nerve. 



It has been customary since the time of Dujardin to compare the 

 pedunculate bodies with the cerebrum of vertebrates and to regard them 

 as an organ of intelligence. Dujardin based his opinion on the fact 

 that these bodies are largest and most elaborately developed in the social 

 I lymenoptera. Leydig and Rabl-Riickard expressed a similar opinion. 



