71 



and ventral columns ; remember the physiological tracts, indistin- 

 guishable in this preparation, that compose the alba. Are the points 

 of exit of the dorsal and ventral roots of the spinal nerve shown in 

 the section? if not, compare with i6i and 162. 



161. Thoracic myel. . Transection. ; 

 stained in toto in ; collodion ; sections jx. 



Compare this preparation with the above, 160, noting (a) the 

 general shape of the myel in the thoracic region, {h) the size and 

 shape of the cornua of the cinerea, (<r) the number and size of the 

 nerve cells in the parts of the cinerea, especially the cells in Clarke's 

 column. Is a lateral horn well defined ? Are issuing fibers of the 

 dorsal or ventral roots shown in the section ? 



162. Lumbar myel, Transection. ; col- 

 lodion ; stained in toto in ; collodion ; sections fx. 



Compare with 160 and 161, noting differences in {a) the' gen- 

 eral shape of the myel, {b) the relative extent of the cinerea and the 

 shape of the cornua, (f) the relative number and size of the nerve 

 cells in the regions of the cinerea, (rf) the obliquely coursing root 

 bundles of the lumbar nerves, constituting the cauda equina. 



163. Myel. Transection. Golgi's rapid method 

 (§ 141) ; collodion ; sections }x. No further treatment ; now 

 in clearer. Mount in balsam without a cover-glass. 



In this preparation there will be outlined by a black precipitate, 

 one or more large nerve cells and their dendrites, so that their ex- 

 tent and branching may be seen better than in 160, 161 or 162, with 

 which comparison is to be made. In addition, there will probably 

 be stained, neuroglia cells, and many neurites running in the 

 cinerea. 



THE (mEDUIvLA) oblongata. 



Gross anatomy. In connection with the study of the follow- 

 ing sections, make a careful examination of the preparations of 

 the brain. Ascertain the location of the oblongata in relation to the 

 myel and the remainder of the brain. Upon the ventral aspect 

 recognize (/) the pyramids with an indication of their decussation, 

 {2) the olives (olivary bodies), (j) the pons, and (^) the cranial 

 nerves springing from this portion, — the Vth to the Xllth. Upon 

 the dorsal aspect with the membranous roof (metatela) removed, 

 there should be noted, (a), the nuclei (enlargements) of the gracile 



