528 'Journal of Comparative Neurology and Psychology. 



but because it brings out clearly the difference between the results 

 of the comparative study of adult brains and the results of a com- 

 plete genetic method in which embryology' contributes its just share. 

 The early development shows that as matter of fact the telencephalon 

 is not added late in the phylogeny but is actually the first segment 

 of the original neural tube in all classes of vertebrates. A certain 

 part of this segment expands and grows in complexity with the 

 increasing complexity of the vertebrate organism and of its mode of 

 life. Further, it is clear that the telencephalon originally contained 

 more than primary and secondary olfactory centers. The existence 

 of the nervus terminalis is evidence of this ; the existence of preoral 

 entoderm and of a well developed neural crest in the telencephalic 

 segment of the embryo is evidence of it ; the existence of a well 

 developed correlating center, the corpus striatum, in the brains of 

 all vertebrates, is further evidence. Of all the authors who have 

 represented the telencephalon as purely olfactory in function, not 

 one has shown or attempted to show that the corpus striatum is 

 accounted for by its relations to the olfactory centers alone. The 

 present w^riter is the only one who has given facts to show the path- 

 way of impulses both to and from the epistriatum and the striatum 

 in lower vertebrates. In my description of the brains of Acipenser 

 (1898, 1901) and Petromyzon (1902) I showed that olfactory tract 

 fibers ended in the epistriatum and that fibers arising from the cells 

 of the epistriatum ended in the striatum. From the striatum the 

 well known basal bundle (Edinger, Van Gehuchten) passed back- 

 ward. These results have been confirmed by Kappers (1906, 1908) 

 but Edinger has persistently disregarded the fact that in his descrip- 

 tions of the forebrain no fiber tracts are ynentioned which would 

 eiwible either the epistriatum or the striatum to carry out any func- 

 tions whatsoever. In the last edition of Edinger's textbook the 

 epistriatum is represented as an end-station for olfactory tract fibers, 

 but no fibers are described in lower vertebrates which go from the 

 epistriatum to any other part of the brain. The striatum, on the 

 other hand, gives rise to the tractus strio-thalamicus, but no fibers 

 are described which come to end in the striatiim. The epistriatum 

 receives olfactory impulses but has no way of giving out any 

 impulses; the striatum has an efferent pathway but receives no 



