34 Effie A. Bead 



rapid Golgi method was used, with results as follows: The olfactory 

 fibrils collect into bundles which go to the glomeruli; these fibers form 

 the outermost layer of the bulb. 



Betzius, 1S92, says that the nerve fibers divide either at a short 

 distance from the glomerulus or oftener near it. After a repeated and 

 profuse dichotomous branching the fibers weave through the glomerulus, 

 but do not form a network. 



Van Gehucliten and Martin, 1891, have seen these fibers bifurcate in 

 the cat and form fibrils of equal thickness, which pass to a single 

 glomerulus, or each may pass to a different glomerulus. Some fibers 

 bifurcate more than once. Thus a single olfactory cell would be con- 

 nected with two or more glomeruli. "This bifurcation cannot be said 

 to be constant but it is frequent." 



The olfactory glomerulus is formed by an interlacing of the termina- 

 tions of the olfactory cells and the dendrites of the mitral cells. These 

 are independent of each other, that is, there is no anastomosis as was 

 thought by Golgi, 1875. Olfactory fibrils were free in the glomerulus 

 of the cat, the dog, the rabbit, the rat and the mouse, and a number of 

 olfactory fibrils go to each glomerulus. 



In the dog they believe the glomeruli to receive dendrites from a 

 great number of mitral cells. In all mammals studied, each mitral cell 

 is connected with a great numl)er of bipolar cells, but each olfactory 

 cell of the mucosa is connected with one, rarely two, mitral cells; at the 

 glomerulus each olfactory fibril terminates generally with only one 

 mitral cell. 



In all animals where the olfactory sense is greatest, each bipolar cell 

 may be in contact with several mitral cells, not because the fiber bifur- 

 cates and goes to different cells, but because in the same glomerulus 

 mav be found the dendrites of several mitral cells. 



Personal Observations. 



The following are the results which Avere obtained from the olfactory 

 bulb of the dog and cat. The olfactory bullj Avas studied in gross prepa- 

 rations and in sections; in the gross dissection the olfactory nerves 

 were traced from the mucosa through the foramina of the cribriform 

 plate to the olfactory bulb. They could be plainly seen lying irregu- 

 larlv upon the bulb (Fig. 4). This was also seen in the transections 

 and saaittal sections of the olfactorv bull) and mucosa. Individual 



