- 5 8- 



and do not come so near to the surface as the posterior. 

 The two crescents are united by an anterior white, and a 

 posterior gray, commissure, between which is found the 

 central canal. In the gray matter a very fine network of 

 fibres is seen. This is composed of medullated fibres, 

 branches of nerve cells, and neuroglia tissue. The nerve 

 cells are usually found in small groups, those in the ante- 

 rior horn are larger and more numerous. The white mat- 

 ter, stained a bluish black, surrounds the gray. It is corn- 

 posed of rnedullated nerve fibres seen in cross section. 

 Between these fibres a small amount of neuroglia tissue is 

 observed. Sketch the cord in outline as seen under low 

 power, and sketch portions of the gray matter of the 

 anterior horn and white matter as seen under high power. 



(c) Cerebellum. 



Small pieces of the cerebellum were hardened in mercuric 

 chloride, stained in Delafield's heematoxylin, embedded in pnraflin, 

 and sectioned at right angles to the small folds. Fix to the slide 

 and mount in balsam. 



Under high power the gray matter shows the follow- 

 ing layers in cross-section : 



(1) An outer molecular layer, composed largely of 

 neuroglial tissue, and containing a few small ganglion cells. 



(2) Between the above stratum and the third a single 

 layer of Purkinje's cells is found. From the base of these 

 cells an axis cylinder process is given off; from the oppo- 

 site pole one or two protoplasmic processes, these extending 

 into the molecular layer and there dividing and redividing, 

 until the process has the appearance of a deer's antlers. 



(3) The granular layer, composed largely of round 

 and spindle-shaped cells possessing comparatively large 

 nuclei, so that in the section very little but the nuclei will 

 be seen. The axis cylinder processes of Purkinje's cells pass 

 through this layer, become medullated, and are lost in the 

 white substance making up the central portion of the fold. 

 Sketch the cortex under high power. 



(d) Cerebral Cortex. 



Small pieces of cerebral cortex were hardened in mercuric 

 chloride, stained in Delafield's hsematoxylin, embedded in paraffin, 



