96 NERVOUS SYSTEM. 



be traced some little way into the molecular layer. The 

 spread of the branches is in a plane transversely to the length 

 of the convolutions. 



Pons Varolii. Man. T.S. (p. 23, s. Eosin, m. B.) Its mass 

 is divisible into a larger ventral portion, in which there 

 are large transverse bundles of fibres interspersed amongst 

 the cut bundles of the pyramidal tracts. The dorsal portion is 

 marked off below by the fillet, a well marked angular tract of 

 fibres. Near the dorsal surface is the aqueduct of Fallopius, 

 surrounded by grey substance (origin of the fourth nerve). 

 Note the dorsal eminences formed by the posterior corpora 

 q uadrigemina. 



Midbrain, crura cerebri and corpora quadrigemina. Man. 

 T.S. (p. the same as the last.) The tegmental (dorsal) portion 

 contains the aqueduct surrounded by a thick layer of grey 

 matter (origin of the third nerve), and shows the prominences 

 of the corpora quad. The crusta (pes) forms the crus proper 

 on each side, and consists of distinct masses separated from 

 the tegmentum by the substantia nigra, which is a broad band 

 of grey matter. The crusta is composed of fibres cut trans- 

 versely, the middle portion of which is the continuation of the 

 pyramidal tract (long motor). Above the substantia nigra in 

 the tegmentum, and placed laterally, is the fillet (sensory tract), 

 whilst near the middle line on each side are the round masses 

 of the red nucleus. 



Cerebral cortex. Man. V.T.S. Convolution, (p. the same.) 

 The grey matter is pink and the medullary is blue, and consists 

 of axons proceeding to and from the grey matter. The posi- 

 tion of the pyramidal cells can be made out. 



Cerebrum. Man. V.T.S. Ascending frontal or parietal 

 convolution, (p. Golgi, 27, s. 24, m. B., uncovered.) (L) Find 



