86 CHARLES BROOKOVER 



sections cut 60 micra thick and represents the nervus terminalis 

 with all non-essential details omitted, as seen from the median 

 side of the olfactory bulb and projected upon the deepest or most 

 lateral of the four adjacent sections. This is one of more than a 

 dozen fishes that show essentially the same thing. 



The above preparations show the nervus terminalis with vary- 

 ing degrees of distinctness from the region of the main ganglion 

 of cells rostrad of the eye-muscle canal along the ventro-median 

 edge of the olfactory nerve until its fibers join the olfactory bulb. 

 A very few impregnated cells have been seen in my preparations 

 (figs. 19, 4), but that this bundle is the nervus terminalis rather 

 than fila olfactoria, is shown by the following facts: it is composed 

 of slightly coarser fibers than the fila olfactoria, arises from the 

 ventro-median part of the olfactory nerve, turns ventro-caudad 

 over the median surface of the anterior one-third of the olfactory 

 bulbs, then caudad, and finally ventro-caudad into the prosen- 

 cephalon proper. Some of its fibers may end in the olfactory 

 bulbs, but a number of them continue into the forebrain. 



The course of the nervus terminalis as seen in horizontal sec- 

 tions is shown in fig. 20. This figure was reconstructed from 

 Golgi preparations in the same way as fig. 19. Fig. 20 shows the 

 nervus terminalis as seen from the ventral side of the brain, 

 projected upon the outline of the most dorsal of the five sections 

 showing the nervus terminalis. In consequence of the more ven- 

 tral sections of the olfactory bulbs being smaller in area and the 

 fact that the mass of the bulbs was slightly shrunken and con- 

 tracted away from the median surface of the olfactory bulbs, 

 the nervus terminalis appears more deeply embedded in the bulbs 

 than is really the case. The real depth of the nervus terminalis 

 is more accurately shown by fig. 21 which is taken from a Cajal 

 preparation of the median side of the adult olfactory bulb at 

 about the middle of its antero-posterior extent. Also, fig. 21 

 shows the cells previously mentioned as of a different nature from 

 the mitral cells, and as being more superficial in position. In one 

 or two Golgi preparations I have found some evidence that fibers 

 believed to belong to the nervus terminalis end in relation to cells 

 on the surface of the olfactory bulbs medianly. 



