8. Explanation of fìguìres. 



All the illustrations have been drawn from preparations of spinal ganglion 

 cells of the pigeon. Camera lucida ^ Zeiss apochromatic objective 1 • 5 mm, and 

 compensating ocular 6 were employed for all except figures 15 and 18 (vide infra). 

 They were reduced by one third in reproduction giving, a magnification of 1,067 dia- 

 meters as they now appear on the plates. This magnification does not however 

 obtain for figures 15 and 18. Unless stated to the contrary, all the sections were 

 cut 4 // in thickness. 



Plate XV. 



1. Fixed in acetic-osmic-bichromate and stained by Bensley's acid fuchsin- 

 toluidin blue method. Mitochondria red, Nissl substance slaty blue, canals as clear 

 clefts and neurofibrils in the axone brown. Note the orientation of the mito- 

 chondria parallel to the neurofibrils (pag. 484). 



'2. Fixed in a cold saturated aqueous solution of potassium bichromate, 

 stained with iron hematoxylin, and counterstained in a l*'/o aqueous solution of 

 erythrosin. Mitochondria black, Nissl substance pinkish gray and neurofibrils in 

 the axone black. Held's third method for neurosomes (pag. 478). 



3. Fixed in Meves' fluid and stained with iron hematoxylin according to his 

 directions. Mitochondria black and Nissl substance gray (pag. 481). 



4. Fixed and stained by Benda's method. Mitochondria blue, Nissl substance 

 reddish brown and the canals as clear uncoloured spaces (pag. 481). 



5. Altmann's osmic-bichromate fixation, stained with acid fuchsin and differ- 

 entiated in alcoholic picric acid. Mitochondria red, Nissl substance yellow and 

 neurofibrils in the axone light brown. Held's second method for neurosomes 

 (pag. 481). 



6. Kingsbury's modification of the Weigert hematoxylin method for mito- 

 chondria. Mitochondria blue-black, and the Nissl substance brown. The myelin 

 sheath and the mitochondria within it are stained the same blue-black color (pag. 486). 



7. Fixed in Altmann's osmic-bichromate mixture and stained by Bensley's 

 copper-chrome-hematoxylin method. Mitochondria blue, Nissl substance very pale 

 yellow and the canals as clear uncolored spaces. A few neurofibrils are visible in 

 the axone hillock stained blue (pag. 483). 



8. Fixed in Carnoy's 6:3:1 fluid, impregnated with silver after Cajal, toned 

 with gold chloride, counterstained in a saturated aqueous solution of safranin and 

 differentiated in 95^0 alcohol. Neurofibrils l^lue-black, canals as clear space and 

 the ground substance red (pag. 497). 



9. Same, counterstained in l°/o aqiieous solution of toluidin blue and differ- 

 entiated in 950/0 alcohol. Neurofibrils dark blue and the Nissl substance light 

 blue (pag. 497). 



