OF DEXISON UNIVERSITY. r, 



though they have no isolated course, but give off side -brauchcs to the 

 dotted substance ; (2) gangHon cells with nervous j^rocesses which lose 

 their individuality and by subdivisions are entirely broken up into slender 

 branches, losing themselves in the dotted substance.'' 



To sum up all, the logical result of Nansen's observations could 

 not long be evaded, and he boldly announces the belief that all gang- 

 lion cells are merely nutritive, or may possibly be also seats of memory 

 apparently regarding those functions as closely allied \ All really ner- 

 vous functions proper, on the other hand are referred to the "intri- 

 cate web or plaiting of nerve-tubes and fibrillae in the dotted sub- 

 stance." Perhaps this is the result to be expected from two implicit 

 reliance upon the method of metallic impregnation. 



Without spending more time in the discussion of these theoretical 

 considerations we may now pass to the study of our sections, and in 

 the present paper confine ourselves to the description of observed 

 structures, reserving their discussion for a subsequent occasion. It, 

 therefore, what follows resembles too closely a bare description of 

 plates, we trust it may serve to prepare for subsecpient comparisons. 



External form and measurements. 



That portion of the brain in front of the bridge is ob-pyriform, the 

 olfactory lobes corresponding to the stalks of the pear. These lobes 

 protrude 9-10 mm. beyond the hemispheres and are attached to their 

 crura by an oblique plane looking dorsad and caudad as well as laterad. 

 The crura are about 5 mm. wide at the attachment and widen caudad 

 to become continuous with the pyriform lobes and, from hemisj>herical 

 prominences, sink to slight elevations whose surface is e.xcavated by 

 vessels from the circle of Willis, which cross transversely about 13 

 mm. from the front. Immediately caudad to this depression the jjyri- 

 form lobe springs ventrad as a strong protuberance. A well defined 

 white band on the ventro-lateral e.\posure of the crural exj)ansion in- 

 dicates the position of one of the external olfactory tracts, which j)asscs 

 parallel to the rhinalis fissure and plunges into the i)yriform lobe near 

 the middle of its cephalad portion. A smaller band lies nearer the 

 median line. The greatest ventral projection of the pyriform lol)e is 

 opposite the infundibulum and it is the posterior free margin of the 

 lobe which constitutes the hii)pocampus, to the inversion of which the 

 protuberance is due. The chiasm lies about 10 mm. back of the ante- 

 rior margin of the hemispheres and there seems to be a small band of the 



