85 



§ 9- Dirediotis for use. Employ this fluid for the isolation of 

 the nerve cells of the spinal cord and of the cerebral cortex, pro- 

 ceeding as follows : 



Split the spinal cord along its median plane, separating thus 

 the two halves, and place it in an abundance of the dissociating 

 fluid. The cerebral cortex should be cut into small pieces by sec- 

 tions vertical to the surface. Allow it to remain in the dissociator 

 from 2-24 hours ; for the best results a stay in the fluid of more 

 than 24 hours is not so satisfactory ; although isolated cells are 

 readily obtained their processes are broken off much nearer the cell 

 body. 



§ ro. Place a fragment of the cinerea of the spinal cord or the 

 cortex of the cerebrum on a clean slide in a drop of ^% eosin in 

 formaldehyde dissociator ; with the blade of a scalpel crush the tis- 

 sue, grinding it thoroughly with a rotary movement, which will re- 

 duce it to small pieces. Gather the debris together, drain off the 

 fluid, and add a drop of glycerin containing ^ij^^ of eosin. Cover 

 and examine, tapping the cover sharply with the handle of the 

 scalpel to shake out the processes of the cells and free them from 

 surrounding matter. Examine, searching for cells with many and 

 long processes. If a satisfactory preparation, seal according to 



§ iio- 



§11. Nitric acid dissociator.* /brwiw/a .• Strong nitric acid, 

 20 c.c. ; water, 80 c.c. This fluid is employed in the isolation of 

 muscle fibers, both striated and plain. The nitric acid acts upon the 

 connective tissue surrounding the muscle fibers, softening and gela- 

 tinizing it so that the fibers may be quite easily separated from one 

 another. 



§ 12. Directions for use. Place in the nitric acid dissociator 

 the fresh striated muscle, gland or organ containing the muscle, — 

 (plain or striated,) — that it is desired to isolate. If it is the inten- 

 tion to work out the anatomy of the muscle or the relation of the 

 muscular coats in an organ, the entire muscle or organ should be 

 taken ; otherwise, portions will suffice. At the ordinary tempera- 

 ture of the laboratory the dissociating action will have been suflicient 



* A more detailed discussion may be found in the original paper : ' ' Stain- 

 ing and Permanent Preservation of Histological Elements Isolated by means of 

 Caustic Potash (KOH) or Nitric Acid (HNfOa)," by Simon H. and Mrs. Susan- 

 na Phelps Gage. /Voc. Am. Soc. of Microscopists. 1889: pp. 34-45. 



