Bedford, Olfactory Na-ve in Szvinc. 409 



the cords unite, is found to be in direct connection with the 

 olfactory lobe of the brain forming a cap over the bulbus. 



13. When established, the nerve is seen to consist of two 

 portions, a lateral and a more median one. 



From observations upon swine embryos, there seems to be 

 no reason to question the peripheral origin of the cellular mass 

 which is connected with the olfactory epithelium by cords, 

 chiefly cellular. At no time, in the development, were any 

 structures observed arising from the brain, which might con- 

 contribute to the formation of this cell mass or to the cords. 



Marshall, von Kolliker, Beard, His, and others have 

 considered these cellular structures to constitute the anlage of 

 the olfactory nerve. That these cellular cords represent, in po- 

 sition, the olfactory filaments that arise later, there can be no 

 doubt. Every stage can be traced from the first appearance of 

 the cords as elevations of the epithelium up to the time of the 

 presence of the olfactory filaments connecting the epithelium 

 with the brain. 



It is quite evident, however, that the majority of the cells 

 of the cords are not the cells from which the olfactory fibers 

 arise. The latter arise from cells the majority of which retain 

 their original position within the olfactory epithelium. Only a 

 few of the neuroblasts migrate from the epithelium. The cen- 

 tral processes of the neuroblasts, located within the epithelium, 

 are seen to be directed toward the cellular cords. In the chick, 

 DissE has been able to trace the processes into the developing 

 cords and finally to the bulbus where they end in glomeruli. 

 My preparations show also some neuroblasts in the act of mi- 

 grating from the epithelium into the adjacent mesoderm. Golgi 

 preparations do not show within the bulbus any indication of 

 the development of neuroblasts which send processes periphe- 

 rally to form olfactory filaments. Since it is known that nerve 

 fibers are continuous with only one nerve cell, we must con- 

 clude that the neuroblasts observed in the olfactory epithelium 

 and which in some cases migrate into the mesoderm are the 



