No. I.] DESMOGNATHUS FUSCA. 26 1 



the mesencephal, where the layer is thickest, the cells are from 

 twelve to sixteen deep. The ectal layer or alba consists of 

 fibers and general supporting substance; scattered around in 

 this layer are isolated cells which appear to have drifted out 

 from the entocinerea. These outlying cells are present in the 

 myel as well as in the brain, but are especially numerous in 

 the dorso-caudal and lateral regions of the cerebrum, where 

 they undoubtedly represent an incipient cortex or ectocinerea. 



Edinger (9), inquiring what sensations may be localized in 

 this rudimentary cortex first appearing in the AvipJiibia, finds 

 '•that the cortex of these animals is connected by a strong 

 system of fibers almost exclusively with the olfactory apparatus. 

 The phylogenetically oldest cortex serves the olfactory sense, 

 and has even thus early certain peculiarities which permit us 

 to consider it closely related to the ammonshorn"; from 

 which it is believed that the olfactory tract connects with 

 higher centers at an earlier stage phylogenetically than any 

 other nerve. Cajal, Van Gehuchten, Kolliker, and others have 

 demonstrated that the first centers of the olfactory nerve lie in 

 the pero or the most ectal layer of the olfactory bulb, and that 

 the fibers connecting them with the cortex are properly pro- 

 jection fibers for the olfactory sense. 



By means of the Golgi method, three forms of cells may be 

 distinguished in the neuraxis of the Desmognatkus : First, 

 those next the neurocoele forming the ental boundary of 

 cinerea, the endymal cells. They agree in all essentials with 

 the descriptions of Oyarzun and others, being pyriform in 

 outline, the blunt end of the cell bounding the cavity or 

 occasionally protruding into it, and the peripheral end extend- 

 ing into a process which divides into numerous smaller ones 

 in the cinerea as well as in the alba. The processes are 

 irregular or ragged in outline and many of them extend as far 

 as the periphery of the neuraxis, where they may end taper- 

 ingly or by means of a slight enlargement. The processes are 

 exceedingly dense and much interlaced, and without question 

 form the greater amount of the supporting substance. The 

 second form of cell is found at the ectal boundary of the 

 cinerea and their outlines vary from a somewhat blunt pear- 



