THE MAMMALIAN NEKVOUS SYSTEM 83 



the spinal cord and brain stem, see Barker ('01), Chaps. XL 

 and XLI; Bailey ('16), Fig. 345, following p. 512; Herrick ('18), 

 Figs. 59, 63, 73, 83, 87; Morris ('14), Fig. 707, p. 898; Piersol 

 ('16), Fig. 946, p. 1905; Quain ('09), Vol. 3, Pt. 1, Fig. 205, p. 

 198. 



In your sections of the spinal cord and brain stem the fibers 

 of the ventral spino-cerebellar tract cannot be separately recog- 

 nized. They ascend in the lateral funiculus and in the medulla 

 oblongata accompany the spinal lemniscus fibers lying super- 

 ficially just dorsally of the inferior olive. In transverse sec- 

 tions of the isthmus region immediately below the decussation 

 of the IV nerves these fibers can be recognized for a short 

 distance on the extreme dorso-lateral surface external to those 

 of the brachium conjunctivum and dorsally of those of the 

 lateral lemniscus. At this point they are turning dorsalward 

 from the brain stem to curve backward into the substance of 

 the cerebellum. 



The superior cerebellar peduncle (brachium conjunctivum) 

 can be easily followed in the sections from the cerebellum for- 

 ward and downward into-the midbrain to its decussation under 

 the aqueduct of Sylvius and its termination in the red nucleus 

 (nucleus ruber) of the opposite side (see Morris ('14), Fig. 638, 

 p. 811, and Villiger ('12), Figs. 178,. 179, pp. 193, 194). 



The brachium pontis is also easily identified in the sections. 



All of the cerebellar tracts mentioned in this section should 

 be entered in your drawings of the cross-sections, using refer- 

 ence books to supplement the incomplete demonstrations of their 

 courses which have been possible in your microscopic sections. 



(c) Summary of the cerebellar peduncles. (See Herrick ('18), 

 Fig. 87.) 



The inferior peduncle (corpus restiforme) is composed chiefly 

 of ascending fibers from the great proprioceptive sensory cen- 

 ters of the spinal cord (dorsal spino-cerebellar tract of Flechsig), 

 from the inferior olive (olivo-cerebellar tract), and from the 

 vestibular root and nucleus of the VIII nerve (vestibulo- 

 cerebellar tract). 



The middle cerebellar peduncle (brachium pontis) is a system 

 of fibers running from the nuclei of the pons to the opposite 

 cerebellar hemisphere. The nuclei of the pons receive impor- 



