556 



THE NERVOUS SYSTEM 



nerve, to the olfactory ~bulb, in which they terminate by end- 

 arborizations that interlace with the dendrites of the mitral olfac- 

 tory cells to form the so-called olfactory glomeruli. 



The neuraxes of the large mitral cells of the olfactory bulbs 

 (olfactory neurones of the second order) are continued as the olfac- 



Fio. 416. DIAGRAM OF THE RELATIONS OF THE NEURONES OF THE OLFACTORY NERVE 



AND OLFACTORY BUI.B. 



olf. c., olfactory nerve cells, located in the olfactory region of the nasal mucosa, whose 

 neuraxes enter the olfactory nerve olf. n, and terminate in relation with the dendrites of 

 the mitral cells, we., in the olfactory glomeruli, gl. The neuraxes of the mitral cells, a., 

 enter the olfactory tract, where they make a sharp bend and pass toward the cerebrum 

 giving off frequent collaterals. At n' a nerve fibre appears to end by a free ramification 

 among the mitral cells of the olfactory bulb. (After Schafer.) 



tory tracts through the medullary center of the bulbs. The central 

 terminals of these fibres are distributed in many directions and are 

 only followed with great difficulty. 



Some of these fibres enter the anterior commissure and decussate 

 to the opposite side ; others enter the columns of thefornix and pass 

 directly to the hippocampus. Still others pass to the mammillary 

 bodies and uncinate gyrus and are thence connected, by neurones of 

 higher orders, with the hippocampus. These latter fibres are possi- 

 bly also connected by fibre tracts with the small ganglion interpedun- 

 culare near the ventral surface of the diencephalon, with the gan- 

 glion habenulce near its dorsal surface, and with the optic thalamus. 



