Herrick, Brain of Certain Reptiles. I2i 



prepararions agrees with that of the Golgi method in showing 

 the axis cyhnders extending entad toward the tract leading to 

 the fimbria. The direction which the processes take is, how- 

 ever, obviously a secondary matter, for in the amphibia, where 

 the embryonic type of cortex is persistent, i. e. the cells do not 

 migrate from the ventricle, the same fibres have a peripheral 

 course and yet can be traced via the homologue of the fimbria 

 to the hippocampal commissure. Figs, j-d illustrate the im- 

 pregnated cells of the hippocampal region ; the former being less 

 highly magnified. 



In the axial lobe a very complicated structure is revealed 

 where it is difficult to get a sufficiently deep stain to bring out 

 the processes in their full extent. Fig. 8-g. show that these 

 cells (see a. Fig. to.) are abundantly provided with processes. 

 The appearance seems to warrant the assumption that we have 

 an invaginated cortex as claimed by Edinger. It is interesting 

 that it is the lateral part which has the fibres brought out ; 

 whether this is solely due to the greater accessibility to the 

 reagents remains to be seen. 



The region for transfer of impulse or switch-station seems 

 to be on the basal aspect, a, Fig. lo, and corresponding regions 

 farther cephalad. Fig. y. illustrates the cells of the ventro- 

 mesal angle of the cerebrum cephalad. The cells seem to be 

 of a kind suitable to facilitate the transfer. Two axis cylinders 

 appear to emerge from each cell, as in the niger, ruber, etc. 

 Fig. 10. is a transection near the supra-commissure, the tract 

 of which is seen at x. The figure gives a fair idea of the 

 fickleness of the silver impregnation. 



The interpretation of the relations in the region where the 

 transition into the diencephalon is aftected is peculiarly difficult. 

 The whole ventro-lateral region is clothed with large pyramidal 

 cells which seem (perhaps spuriously) to connect with the 

 peduncular fibres. If one could trust appearances it would 

 seem that the supracommissure tract blends with olfactory radix 

 fibres and passes to the occipito-basal lobe (sphsricus.) A 

 smaller tract leaves the supracommissure tract and passes mesad 

 and caudad into the diencephalon. The peduncles (basal fore-brain 



