CELLS OF THE NERVUS TERMINALIS OF THE RAT 105 



to which the general term 'fila' may perhaps be best applied, 

 are greatly increased in number. The central growth of the 

 fila has carried the cell bodies situated among them centrally, 

 thus somewhat displacing the olfactory ganglion. This, coupled 

 with the enlargement of the forebrain, tends to mold the gan- 

 glion-like aggregate to the forebrain contour. Certain few 

 cells of the aggregate show a marked rounding-out of nuclei and 

 a distinct cytoplasmic ring quite characteristic of a neuroblast. 

 Others are undoubtedly destined to become sheath cells. Many 

 seem indifferent. The author consequently would admit the 

 partial correctness of Dollken's designation of the 'olfactory 

 ganglion' of older writers as ganglion terminate. Reference to 

 the figures of Disse showing early stages in the development of 

 the olfactory fila would seem to indicate quite clearly the pres- 

 ence of neuroblasts in the midst of the fila — neuroblasts which 

 undoubtedly would tend to intermingle with sheath cells and 

 join with them in the formation of the so-called olfactory gan- 

 glion. It may be noted that certain fila at this stage arise from 

 a portion of the epithelium which may be definitely marked out 

 as vomeronasal. 



I have been unable to trace cell-bearing ophthalmicus strands 

 into territory where their addition of elements to the neuroblasts 

 situated among the fila would seem possible. The same obtains 

 for what would seem a vastly more probable source of addition, 

 namely, the facialis. At this period the grouping of cells which 

 marks out the site of the future sphenopalatine ganglion is 

 clearly evident. From it cellular strands have been traced to 

 the most posterior part of the olfactory sac in the vicinity of 

 Hochstetter's membrane. These strands, however (and they 

 have likewise been followed in a pyridine-silver preparation of an 

 embryo two hours older) , do not approach the cell aggregates 

 accompanying the fila; they have not been observed to enter 

 the epithelium. It would appear to the writer that an addition 

 of ganglion cells to nasal territory, especially of any whose proc- 

 esses were related to vessels and glands, would be most prob- 

 able from this direction. The facialis nerve is accompanied by 

 elongated cells which the author has had reason to believe give 



