420 ANATOMICAL TECHNOLOGY. 



In Menobranchus the cerebellum is very narrow, its caudal margin is not dorsiverted, 

 there is no furrow between it and the optici, and it is distinguishable from them mainly 

 by the absence of pigment. 



The diencephalon is decidedly narrower than the parts cepha- 

 lad and caudad of it and is partly covered by their projections, and 

 the mesal furrow is less deep than between the optici. In Meno- 

 branchus its caudal limit is not easy to assign. 



Upon the cephalic part of the diencephalon rests the conarium 

 (or its continuation, 1084) ; this body is not round, as almost uni- 

 versally shown, but oval, and anteverted so as to rest also upon the 

 roof of the aula. 



If the cephalic (really dorsal) end of the conarium is cautiously 

 elevated, there will be exposed a delicate membrane, the aulatela, 

 or roof of the aula. 



The hemispheres, the largest portion of the prosencepTialon, con- 

 stitute the widest part of the brain with Menobranchus, and the 

 longest in both it and the frog. In the latter they are compressed, 

 in the former depressed. As already indicated, their caudal ends 

 flare laterad so as to partly embrace the diencephalon and nearly 

 reach the optici in the frog. Their mesal surfaces are in contact, 

 but may be separated in the cephalic part by blowing between 

 them or by a beaded bristle. 



At the cephalic end of each hemisphere is attached the corre- 

 sponding Lobus olfactorius, the lateral half of the rhinencephalon. 

 The Nerni olfactorii may be traced thence to the nasal capsules. 

 The lobes are separate in Menobranchus as in most Vertebrates, 

 but in the frog and other Anura they are united by connective tis- 

 sue constituting a pseudo-commissura. 



1096. Dissection of the Amphibian Brain. The arachnoidea 

 and the metalela have been removed as directed in 1095. 



Instruments and Material. Tripod magnifier ; fine forceps ; 

 beaded bristles ; very sharp scalpel, preferably small ; fine scissors ; 

 syringotome or tracer ; flexible blowpipe ( 138) ; alcohol or glycerin 

 as directed in 1094. 



Note at the bottom of the metacrelia a mesal furrow, which is 

 continuous caudad with the canalis centralis of the myelon. 



With the flexible blowpipe, blow cephalad under the cerebel- 

 lum, and note that all the parts of the brain are inflated, showing 

 the existence of a continuous series of cavities, as represented in 

 Fig. 110. 



