ON THE BRAIN OF THE COCKROACH. 355 



back of the brain to join similar fibres from the opposite 

 side. 



Antennary lobes. — These are large in the cockroach, and 

 in sections present very much the same structure as Dietl 

 has described in the bee. In whatever direction they are 

 cut they present the appearance of being composed of a 

 number of large cell-like bodies, with fibres passing in 

 betAveen them in every direction, the whole being surrounded 

 by a layer of large ganglionic cells. The interior cell-like 

 bodies are found throughout the mass of the antennary 

 lobe in the cockroach, whilst in the bee they are confined 

 to the periphery. When examined more closely the large 

 cell-like bodies are found not to be cells, but to be made 

 up of a delicate network of fibres, as described by Dietl 

 and Flogel. It was only with a high magnifying power 

 ("iV immersion) that this network could be traced, and then 

 it was by no means distinct ; the interspaces still appeared 

 granular, Avith minute translucent spots. The spaces 

 between the rounded bodies are seen to contain cells as well 

 as fibres ; indeed, it maybe said that the cortical ganglionic 

 cells extend into the interior of the lobe. The fibres anas- 

 tomose with each other, and are continuous, on the one 

 hand, with the fine network of the rounded bodies, and, on 

 the other, with the antennary and commissural nerve-fibres. 

 The ultimate structure of these rounded bodies is very 

 similar to that of the ccdices, but it is coarser, and many of 

 the transparent spaces are much larger. 



From the inner side of the antennary lobe fibres are given 

 off', which pass under the trabecules, and unite with similar 

 fibres from the opposite side. Posteriorly, this lobe is con- 

 nected with the oesophageal commissure, and certain fibres 

 may be traced inwards to the cells around the corpus 

 centrale. 



Just below the antennary lobe, and in the oesophageal 

 commissures, close to the spot where the nerve to the frontal 

 ganglion arises, there is a small rounded body, composed of 

 dots of granular matter, not unlike that of the calices. 

 This body seems to be the homologue of a similar 

 structure in the mole-cricket described by Dietl. I 

 have not been able to trace its relations to the surrounding 

 parts. 



Cortical ganglionic cells. — The brain is almost surrounded 

 by these large cells, excepting above, in the region occupied 

 by the corpora fungiformia, and, probably, they do not 

 extend over the cauliculi. These ganglionic nucleated cells 

 vary much in size, some of them being very large, and they 



