84 CHARLES BROOKOVER 



I have never been able to satisfy myself that there are not ol- 

 factory fibers in this bundle even when separate. We have seen 

 how it is sometimes united with the olfactory nerve in the 100 mm. 

 stage, and the previous embryological account shows that it is 

 developed as a part of the olfactory nerve. 



Nissl preparations show that cells of the same general character 

 as those just described, are continuous over upon the surface of 

 the olfactory bulbs without any line of demarcation. Here 

 they lie in groups of from two to as many as ten. They are situ- 

 ated outside the glomerular zone among the olfactory fibers 

 and just inside a more or less continuous layer of neuroglia (fig. 

 21), from which they can be distinguished by their staining re- 

 actions in the Nissl preparations. Their size is larger than that 

 of the supporting elements, but they are only about half as 



sheaik cells 



Fig. 18. Cells in proximal part of nervus terminalis as it joins olfactory bulbs. 

 Sagittal section showing the dendrites tapering proximally. Shows sheath cells 

 characteristic of the olfactory nerve. Toluidin blue stain. X 340. 



large as the mitral cells which lie at a deeper level beneath the 

 glomerular zone. An estimate showed that there are at least 

 two hundred cells that may confidently be said to belong to this 

 category, on a single olfactory bulb. They are slightly more 

 numerous on the mesial side of the bulbs but some were found in 

 other positions as well. The majority of these cells appear to be 

 bipolar. Catois ('01) has described such extra-glomerular cells 

 in the olfactory bulbs of teleosts. Disse ('96) has found cells in 

 Golgi preparations of embryo birds in the same position as those 

 I have described in the olfactory nerve (nervus terminalis) of 

 Amia where it joins the bulbs. Also, Rubaschkin ('03) has found 

 peripheral cells in the frog's olfactory bulbs, which he denominates 

 "sub-glomerular. " Similar cells have been shown by Rubasch- 



