3J) 



Lesson XIV. 

 NERVE CELLS. 



(a) Nerve Cells from Spinal Cord. 



The gray matter \vas dissected from the cervical cord of an ox, 

 macerated for several days in a very weak solution of chromic acid 

 (1-15,000), and was then stained in lithium carmine. Tease very 

 carefully in gum glycerine, controlling the results under the low 

 power. Aim to isolate the cells from the surrounding tissue. The 

 worth of this preparation will depend very largely on the care with 

 which it is teased. 



Examine under high power, and observe the large 

 branching nerve cells; try to make out the axis cylinder 

 process. Sketch several cells under this power. 



(b) Nerve Cells from tlie Spinal Cord Stained in 



Methylene Blue. 



The gray matter was dissected from a spinal cord, and crushed 

 between two cover glasses, these are then drawn apart, and set 

 aside to dry. Stain for 30 minutes in a 1% methylene blue solution, 

 wash in water, and dry between filter paper. "When thoroughly dry 

 mount the preparation in balsam. 



Study the preparation under high power. A few 

 nerve cells will be found. Observe the relatively large 

 nucleus with its prominent nucleolus ; also the spongio- 

 blastic network in the cell body. Sketch as seen under 

 high power. 



(c) Spinal Cord Stained after Golgi's Method. 



The spinal cord of an embryo or young mammal was divided 

 into small pieces, placed for 2 or 3 days in a solution composed of 1 

 part of a 1% solution of osmic acid and 4 parts of a 3% solution of 

 potassium bichromate, then in a }4% solution of silver nitrate for 

 about an hour, finally in a ^4^% solution of the same salt in which 

 they remained for 2 to 4 days, then surrounded with parafliu, and 

 sectioned. The sections were cut into 9d% alcohol, transferred to 



