THE CEHEBEUM OR PROSENCEPHALON. 



149 



studied the relations in fishes and reptiles and has determined that, in the 

 recurrence of the same relation in animals so far remote from each other in 

 the series, we have to do with a fundamental principle. This newly out- 

 lined portion of the brain, which always lies close to the corpus striatum, I 

 have designated the Episiriatum. 



The Epistriatum is most sharply defined in the reptilian brain (see Fig. 

 97), where it is also differentiated in its minute structure (compare also 

 Fig. 118). 



In amphibia the fibers of the olfactory tract are, for the most part, non- 

 medullated, and in birds very sparingly so, since these animals have a 

 somewhat atrophic olfactory apparatus. Hence it has not been possible to 

 demonstrate, in both, the course of the fibers in question or the location of 



Fig. 97. — Brain of the lizard (Taranus), showing the course of the median 

 fibers from Bulbus olfaetorius and the Epistriatum. Lob. olf. post., with its 

 fibers, not shown. 



the Ogl. epistriaticum . In mammals the tract from the bulb is well known. 

 One sees it pass backward on the base of the brain, and recognizes that 

 bundles pass continuously from it into the Lobus olfaetorius posterior, 

 possibly into the cortex of the Lobus olfaetorius anterior. The posterior 

 end has, as yet, not been with certainty located. It is possible that the 

 structure known as ISTuc. amygdalae corresponds to the Epistriatum of the 

 lower vertebrates. 



The median portion of the secondary olfactory tract ends, then, in the 

 Epistriatum, while the lateral portion ends farther ventral in the Lotus 

 olfaetorius posterior. 



Even in the teleosts — the carp, for example — one sees that, lateral to 

 the large bundles en route to the epistriatum — viz., the median fasciculus — 

 smaller bundles pass into the area olfactoria. This lateral olfactory fascicu- 



