104 CHARLES BROOKOVER 



impregnated does not show more than five or six fibers, and there 

 is slight diminution in numbers forward. As we have seen 

 (fig. 22), there may be as many as six fibers impregnated at this 

 age at the level of the anterior end of the olfactory bulbs. It 

 will be noted (fig. 32) that a lateral branch is given off medianly 

 at the level of the anterior edge of the anterior commissure which 

 is drawn in position by the aid of the camera lucida. There is 

 always a pair of arteries entering the forebrain at the level of the 

 anterior edge of the anterior commissure and in one instance in 

 Cajal preparations of adults I thought I found a fiber entering the 

 brain along with the artery, but this is the only instance I have 

 ever been able to find of fibers entering the ventral surface of the 

 brain between the posterior part of the olfactory bulbs and the 

 optic chiasm, although I have searched carefully in all of my 

 preparations. 



On the. opposite side (fig. 32) fibers reach the same point near 

 the anterior commissure and continue forward along the blood 

 vessels near the mid-line as far as the anterior median margin of 

 the olfactory bulbs. At the level of the sulcus olfactorius the 

 internal carotids always give off one or more branches medianly. 

 These branches turn dorsad in the fold of pallium which Kappers 

 ('07) shows as separating the common forebrain ventricle into 

 lateral halves at its anterior end (fig. 30). In a fish which had 

 its medulla oblongata and spinal cord pithed, I have watched the 

 blood circulating dorsad in this region to the neighborhood of the 

 anterior end of the pineal stalk (fig. 30). In Cajal preparations 

 I had traced fibers along the course of these arteries from a com- 

 pact bundle of six or eight fibers at the level of the posterior ven- 

 tral margin of the olfactory bulbs until they scattered beneath 

 the paraphysis (fig. 30). Finally in three out of four Golgi prepa- 

 rations of adults made at one time, I confirmed my findings 

 in Cajal sections and came to regard the fibers in this position 

 as a constant feature. They are non-medullated and their maxi- 

 mum number does not exceed twelve in adult Amia. Almost 

 invariably when the conditions have been favorable for impregna- 

 tion of these fibers in their protected position they have failed 

 to impregnate in Golgi and Cajal preparations the fibers in the 



