456 THE XltRVOUS SYSTEM. 



Fig- 3), and are only connected with the rest of the brain by 

 t\vo pairs of bundles of fibres, the peduncles and the pedicles. 



The Peduncle is a short, thick, round cord, which enters the 

 under side of the procerebral lobe (PI. XXX., Fig. i) near its 

 inner angle, and connects it with the thalamic lobe. It receives 

 a considerable bundle of fibres from the trabecula, and another 

 from the antennal (olfactory) ganglion. 



The Pedicle is a slender bundle of fibres, which passes from 

 the nodulus to the procerebral lobe (PI. XXIX., Fig. i). 



The Commissure of the procerebral lobes is a thick median 

 band of transverse fibres, which connects the two procerebral 

 lobes with each other ; it lies immediately behind the com- 

 missure of the antennal ganglia. 



The Nodulus (PI. XXIX., ;;) is a very remarkable spheroidal 

 body, which is connected with the hilus of the corpus centrale 

 by a single slender, round, median cord. This cord, which 

 may be termed the fillet of the nodulus, consists of fibres 

 which radiate from each other in the substance of the corpus 

 centrale. They apparently pass through the nodulus into the 

 pedicles of the procerebral lobes. 



iH.-i RIM IIIN OF Pi. A IT. XXX. 



Details of the anatomy of the brain of the Blow-fly imago. All the figures in this and 

 the three succeeding plates were drawn from sections to the same scale with a 

 camera lucida and a half-inch objective. 



FIG. i. A frontal section of the brain of an adult Blow-fly, between the antennal 

 ganglia and the corpus centrale, drawn from the tenth section of a series numbered 

 from before backwards. The plane of the section is slightly oblique from before 

 backwards and above downwards : <Y, procerebral lobe ; ft; outer fibres of the 

 crus ; /, frontal lobe of mesocerebron ; /, infra-rcsophageal ganglia ; t, lateral 

 lobe of mesocerebron ; n, nodulus ; ///, thalamon ; tr, trabecula ; / /, internal 

 tubercle ; la, anterior tubercle. 



I-'i'.. 2. -An oblique section of the brain of a Blow-fly, making an angle of about 45" 

 with the frontal plane. The plane of the section is from above and behind, 

 downwards and forwards. It passes through the posterior part of the corpus 

 centrale behind and below the brachia : t f, corpus centrale ; /, infra-rcsophageal 

 ganglion ; HI, superior lobe of the mesocerebron ; ;///, internal medullary mass 

 of the optic ganglion ; /, peduncle of the corpus centrale ; th, thalamon ; //, 

 trabeculu . 



FIG. 3. A lateral section of the same, immediately above the oesophagus : a, an- 

 tcnnnl lobe; f>; ascending fibres of the cms ; ^ ft; ganglion of the crus, with 

 two bundles of ascending fibres on its inner surface ; ///, lower lobe of the 

 thalamon. 



