184 PROCEEDINGS OF THE ACADEMY OP [1883. 



None of these cortical exposures of the central gra}' can be 

 considered to correspond to the cortical gray (Rindengrau) of 

 the mammalian brain. The gray substance is, therefore, chiefly 

 central. 



The scattered nerve-cells above referred to are principally found 

 in the substance of the hemispheres above the cavities, internal 

 to fig. 11, a. Here they are numerous. 



The nerve-cells are chiefly small, oval and nucleated bodies, 

 very compactly placed ; among these at some points, as in the 

 crura, much larger cells enveloped in loose capsules were discov- 

 ered. No processes were found leading out of these cells, in fact 

 no unmistakably branched cells were found at any point ; this 

 may have been the fault of the preparation methods, for Stieda 

 has found that the branched nerve-cells are very numerous in the 

 frog, while Wyman, emplojdng simpler histological methods, failed 

 to find them. 



This is as far as the sections have been studied, although they 

 offer very tempting opportunities for making out the nerve-tracts. 



The following is a resume of the results thus far obtained : 



In external characters, Amphiuma differs widely from the frog 

 type in the simpler differentiation of its parts, the mid-region of 

 the brain being a rounded tube with no separation of its optic 

 lobes and thalami indicated above. The cavities of the brain are 

 equally simple, the meta-, meso- and diacceliae forming a uniform 

 cavity, forking into the procoeliae in front. The infundibulum has 

 the large size which is so characteristic of it in the fishes, and its 

 lateral bodies recall the lohi inferiores in the Teleosts, although 

 passing forwards they form the tuber cinereum. The pineal and 

 pituitary bodies are constructed upon clearly different principles, 

 one being within, the other without the brain walls, the former a 

 vascular plexus, the latter a gland. In the roof of the Dien- 

 cephalon is a small spherical body whose meaning is not known, 

 but which may prove to be of some morphological significance. 

 The cerebellum has a cellular investment and consists of two sets 

 of fibres with a transverse and fore and aft direction. The gray 

 matter of the brain lines the cavities throughout, as the " central 

 graj^ ; " continuations of it extend in some places to the cortex, 

 but the "cortical gra^^," if present at all, is verj- limited in 

 distribution. 



