Bedford, Olfactojy Nen>e in Szvine. 395 



nate within the olfactory epithelium. Disse, however, believes that 

 the majority of the neuroblasts never leave their position within the 

 olfactory epithelium. A very few do pass into the mesoderm separat- 

 ing the olfactory epithelium from the brain and there undergo their 

 transformation into bipolar ganglion cells. He also believes, as does 

 His, that the cellular anlage of the olfactory nerve, which has been 

 seen by various observei's, arises from cells that migrate from the olfac- 

 tory epithelium, but these cells, according to Disse, instead of becom- 

 ing neuroblasts are destined to form the cellular nerve sheath. Thus 

 he believes that the cell mass, which by other investigators has been 

 considered to be the anlage of the olfactory nerve, is of very slight 

 importance in the formation of that nerve. He failed to obtain satis- 

 factory results from the use of the Golgi method in the study of 

 mammalian embryos. 



Even if Disse's work be accepted as representing the true con- 

 dition in the chick* it does not necessarily follow that the course of the 

 development of the olfactory nerve is precisely the same for mammals. 



The observations of His, von Kolliker and Chiarugi, only, are 

 based upon the study of mammalian embryos. In Beard, von Kol- 

 liker, Chiarugi, His and Disse, whose work has been done since 

 1884, we have five investigators, no two of whom are in entire 

 agreement as to the origin of the olfactory nerve. Chiarugi's con- 

 clusions, based upon the observation of mammalian embryos, differ 

 very essentially from those arrived at by His and vox KOlliker in 

 the study of animals of the same class. His and von Kolliker in 

 turn do not agree as to the relation of the cells to the fibers of the nerve 

 and neither of these investigators employed the Golgi method by the 

 use of which Disse reached in the chick very different conclusions as 

 to the position of the neuroblasts from which the fibers arise. 



Scope of This Paper. 



It is evident that there is need of more observations re- 

 garding the origin of the olfactory nerve. It is especially de- 

 sirable to ascertain whether the conclusions arrived at by Disse 

 for the chick can be extended to mammals. 



Since the conclusions of the different investigators vary, 

 the following pertinent questions have not, as yet, for mammals 

 been conclusively answered. 



I. When and where do the first indications of the olfactory 

 nerve appear ? 



