57 



Lesson XV. 



SPINAL CORD, CEREBELLUM, AND 

 CEREBRUM. 



(a) Spinal Cord with Anterior and. Posterior 

 Roots. 



A segment of tlie cervical cord of ;i cat witli the aiitcridr and 

 posterior roots of the two sides (to a i)()int a shoit ilistancc l)eyontl 

 their junction) was removed aiid hardened in niercnric cidoi'ide. 

 To insnre tiie hardening: of the roots in a |)lane so tlial Ihc cord and 

 roots on botii sides niitrht l)e cut in one section, the following de- 

 vice was made nseof : An oiMMun'^' hirge enough to admit tiie cord 

 was mu<h^ in a card; one end of the cord segment was puslipd 

 tlironudi tiiis opening, and t'le roots were spread out on the card to 

 whicii they adinM'ed. The prcpni'ation was then jilaccd in mei'cniic 

 ciiloride. After iiai'dening it was stained en mit.-<xe in huiax carmine 

 for several days, embedded in }Kiniffin, and sectioned. Fix to the 

 slide, and mount in ))alsam. 



Study under low power. Observe the anterior iiiid pos- 

 terior roots in connection with the anterior and posterior 

 horns of the Ki'^iy matter. Sketch under low power. 



(h) Section of Spinal Cord Stained in Weigert's 

 Hj^matoxylin. 



A liniiian conl was hardened in ]\Iuller's tluid, em1)e<lded in 

 celloi<lin, staineii in Weigert's hfematoxylin, deliydrated, and 

 cleare<l in c.arbol-xyloi. Place section on slide, wipe away excess of 

 clearing finid, and mount in balsam. 



Stud}' under low power. The cord is nearly divided 

 into two symmetrical htdves by two fissures, the anterior 

 and posterior median fissures, the hitter is really only a 

 connective tissue septum. In each half of the cord the 

 gray matter, which in this section has a yellowish-brown 

 color, appears in the form of a crescent. The convex 

 borders of the two crescents are opposed to each other. 

 The anterior horns of gray matter are broader and shorter, 



