THE EMBRYOLOGY OF THE HONEY BEE 119 



posed of a thick plate of cells whose cytoplasm in many prepara- 

 tions stains more deeply than the remainder of the brain, and 

 whose nuclei are unusually large, clear, and sharply stained ( Figs. 

 39 and 44 x). 



The second or middle lobe of the protocerebrum (iBr 2 ) is 

 very short, its length being about one-half its width. 



The third lobe (iBr 3 ) is about one-third the length of the cor- 

 responding lateral half of the protocerebrum and at its anterior 

 end meets its mate of the opposite side and is here united to it 

 by the supraoesophagael commissure (Fig. 43, SupCom). 



The deutocercbrum, or antennal lobes, the second division of 

 the brain (Figs. 39, 40 and 41, 2Br [AntL] manifests itself ex- 

 ternally as a pair of conspicuous rounded swellings of the antero- 

 lateral face of the brain just above the oesophagus and below 

 the protocerebral lobes. From the fibrous core of each of the 



StgNv 



Oe(Flnt) 



AntN 



1 Ten 



aBr 



3 Br 



"•SoeCom 



SlkDO 



SoeGng 



Fig. 41. Transverse section through the head of a newly hatched larva 

 (Stage XV) intersecting the circumoesophageal commissure and showing 

 part of the protocerebrum (iBr), the deutocerebrum (2Br), the tritocere- 

 brum (jBr), and the anterior end of the suboesophageal ganglion 

 (SoeGng), x 337. 



