98 WILLIAM TOWNSEND POIiTER, 



DESCRIPTION OF PLATE XII, bis, 



Illustrating Dr. William Townsend Porter's paper, " The 

 Presence of Ranvier's Constrictions in the Spinal Cord of 

 Vertebrates/^ 



Figs. 1, 2, 3, 4, 5. — White substance near median fissure. Ox. Osmic 

 acid 2 per cent., nitrate of silver 1 per cent., each 1 part, two hours. Dilute 

 solution of caustic potash, about five minutes. Teased in glycerine diluted 

 about one third with distilled water. Leitz, -j^., ocular 3, draw-tube out. 



Fig. 6. — Spinal Cord. Guinea-pig. Osmium-silver mixture as above, 

 three hours. Teased in diluted glycerine. Leitz, -j~, oc. 3, d. t. out. 



Fig. 7. — Medulla oblongata. Rabbit. Osmium-silver mixture, two hours. 

 Picro-carmine, twenty-four hours. Teased in diluted glycerine. Leitz, yV> 

 oc. 1. Axis-cylinder shows three silver cross-stripes at constriction ; the 

 lines between the ends of the medullary cylinders represent the light reflex. 



Fig. 8. — White substance near median fissure. Spinal cord. Ox. Osmic 

 acid 2 per cent., twelve hours. Celloidine, cloves, balsam. Leitz, J^, oc. 3, 

 d. t. out. The section was cut the average thickness of the fibres. 



