240 PRACTICAL HISTOLOGY [XXXI 



8. Section of spinal cord (alcohol) in paraffin. Fix to a 

 cover-slip and stain the basophil granules and masses in the 

 cells as in Lesson xv. 3, a. 



9. Golgtfs chromate of silver method modified by Ramon y 

 Cajal. Place some small pieces of the spinal cord of a chick 

 (about 12 days after hatching) or of a festal mammal in about 

 20 volumes of Golgi's osmic-bichromate mixture (p. 247) and leave 

 in the dark. After 2, 3, and 4 days rinse a piece for an instant 

 with distilled water, and put at once in *75 p.c. silver nitrate, 

 and leave for a day or more in the dark. Einse as before, and 

 repeat from the beginning. 



Place the piece in 95 p.c. alcohol for 10 to 15 minutes, 

 imbed superficially in paraffin (p. 58), and cut at once, moistening 

 the razor with 95 p.c. alcohol, place the sections on a thin cover- 

 slip, sop up excess of fluid, press lightly with smooth tissue 

 paper, add a drop of xylol or bergamot oil, sop this up and blot, 

 cover with xylol or balsam, place at about 40 C. to dry. Fix 

 two pieces of thick cover-slip to a slide a little distance apart, 

 and on these fix the slip with the specimens downward. 



The pieces may also be cut frozen, washed quickly in water, 

 dehydrated rapidly with absolute alcohol, cleared and mounted 

 in xylol balsam ; but they are more apt to become decolourized 

 than by the former method. 



10. Beginning of decussation of pyramids. 



Section of upper part of 1st cervical segment. Note 



The numerous bundles of fibres surrounded by grey 

 substance about the level of the central canal ; decus- 

 sating bundles cut obliquely at the base of the anterior 

 fissure, which may be very shallow; a wedge-shaped 

 bundle of fibres more or less obliquely cut on the 

 median side of each anterior column. (Fibres of the 

 pyramid crossing to the lateral pyramidal tract of the 

 spinal cord.) 



