Hardesty, Medulla Spinalis of the Elephant. i8i 



fasciculi gracilis ; N. n. h.. Nucleus nervi hypoglossi ; O. a. 711., Nucleus oli- 

 varis accessorius medialis ; O. /'., Nucleus olivaris inferior; /"., pyramids; S. £'. 

 J^., Substantia gelatinosa Rolandi. 



PLATE XI. 



fi^. ^. Transverse section throu;^h decussatio pyramidum and caudal 

 portion of nucleus iasciculi gracilis. Photograph. X 3- 



Fig. ^. Companion to Fig. 4. D.p., decussatio pyramidum; F. c. i., 

 fasciculus cerebro-spinalis internus; Other references same as in Fig. 3. .Slightly 

 diagrammatic as to decussating pyramidal axones. 



f'ig. 6. Detail from Fig. 4. Involving the region between the columnae 

 anteriores and showing the general course of the decussating pyramidal axones 

 as they pass from the pyramid below to collect in the fasciculus cerebro-spinalis 

 internus above. The magnification is not great enough to show the axones 

 themselves but their beginning course is indicated by the arrangement of the 

 connective tissue trabeculae. The open spaces are blood vessels. X i '• 



Fig. 7. Transverse section through Vlth cervical segment of the medulla 

 spinalis. Photograph. The dark bodies in the lower left of the figure are fila 

 radicularia of the radix anterior which by accident were folded under in niount- 

 ing the celloidin section. Other such fila are vignetted out of the print. X 3- 



Fig. S. Companion to Fig. 7. A. s. a., arteria spinalis anterior; C. t). a., 

 commissura alba anterior; F. c. /., fasciculus cerebro-spinalis internus; 1'. g., 

 fasciculus gracilis ; R. /., radi.x posterior. The position of the canalis centralis 

 is sliown. 



J'LATE XII. 



Fig. Q. Detail from Fig. 7, showing the fasciculi cerebro-spinales interni 

 as they are situated in the commissura grisea between the dorsal portioa con- 

 taining the canalis centralis and the coiiimissura alba posterior, ami ilie ventral 

 or commissura alba anterior. Numerous iilood vessels are shown. X i". 



■ Fig. 10. Detail from transverse section through the IVth Thoracic seg- 

 ment. On same scale as Fig. 9. Shows appearance and decr^.i-e in size of 

 fasciculi cerebro-spinales interni and the size and appearance ol the nucleus 

 dorsnlis at this level. The angle of the columnae posteriores may lie noted, 

 and on the lower left of the figure the thickness ofthecolumna anterior. X 'O- 



Fig. 11. Photograph of transverse sections from \'IIIth Thoracic segment. 

 Showing the proportional amount ol substantia grisea at this level, the general 

 shape of the gray figure, columnae posteriores and anteriores, the appearance of 

 the fasciculi cerebro-spinales interni, the nuclei dorsales, the relative thickness 

 of the dura mater spinalis, etc. X 3- 



Fig. 12. Companion to Fig. il. N. d. {C. c), nucleus dorsalis (Cl.a^RKE's 

 column) ; Other references same as in Fig. 8. F. g. and F. c. /., much less than 

 in cervical VI (Fig. 8). 



Fig. I J. Detail from Fig. 11. Given to compare appearances of the fas- 

 ciculi cerebro-spinales interni, nuclei dorsales, columnae anteriores and com- 

 missura grisea with appearance of these structures as given on same scale in 

 Figs. 9, 10, 14, and 15. X lO- 



Fig. /./. Photograph of central region of transverse section through 



