Bedford, Olfactory Nej-ve in Swine. 



399 



of these cells are more nearly spherical than the nuclei of 

 the prismatic cells, the nuclei of the latter being usually ellipti- 

 cal, their long axes corresponding with the long axes of the 

 cells. The nuclei of the rounded cells are not provided with a 

 nuclear membrane and present a ragged outline. As has been 

 often suggested, they are probably mitotic cells. 



Developmeyit of Neuroblasts. — In slightly older embryos, 

 in addition to the spherical cells, cells of a slightly different 

 shape are present, which, from their size, appearance and loca- 

 tion, evidently belong to the same class of cells as the spherical 

 cells described. They are pear-shaped with the pointed end 

 directed away from the outer edge of the epithelium, toward 

 that marg-in bordering' the mesoderm. 



Pig' 3- Various stages in the development of neuroblasts observed in the 

 olfactory epithelium of a swine embryo 7 millimeters in length. The line above 

 each figure represents boundary between epithelium and the lumen of the nasal 

 pit. X Soo; iron haematoxylin, 



In a number of cases this pointed end passes into a fine 

 fiber extending toward the mesodermal margin of the epithe- 

 lium. In the majority of cases, the peripheral end is very 

 slightly pointed, while in other cells a well developed, con- 



