and Laboratory Methods. 



1987 







Staining Axis-Cylinders of Fresh Spinal Chord. 



The convenience of the method here described for the demonstration of the 

 structure of the meduUated nerve fiber is the justification for presenting it. I do 

 not recall having seen just this method recommended, but it has doubtless 

 occurred to many ; it may, however, interest some. The material used was a 

 part of the spinal chord of a calf obtained at the butcher's. Though the calf had 

 not been just previously killed, still the structure of the nerve had not deteriorated 

 seriously enough to interfere with the demonstration. I have found that butcher's 

 meat, very likely as a result of its refrigeration, is often quite adequate for use in 

 making out many of the coarser points in histology and much more convenient 

 than any other source of material. A small piece of the white part of the chord 

 is placed in 30 per cent, alcohol and kept in an oven at 56°C. for (3 hours. 

 After this maceration, which loosens the fibers from one another, small pieces 

 are removed to a glass slide and teased apart in distilled water, and a cover-glass 



is placed on them. The 

 fibers are now separated and 

 at places ends are seen run- 

 ning out into the water. An 

 aqueous solution of acid vio- 

 let (Gruebler's) is now made 

 by adding to a few crystals 

 of the dry stain a few drops 

 of distilled water. The 

 strength of the solution is not 

 of importance. The mount 

 is now irrigated with this so- 

 lution and the fibers are 

 kept under observation during the process. It acts very quickly, and will stain 

 the protoplasmic part of the fiber, i. e., axis-cylinder, almost at once. The 

 stain passes down the axis-cylinder, becoming fainter and fainter. After a 

 short time the action is suspended by irrigating with water, and the appearance 

 shown in the figure results. 



In such a preparation there was no difficulty in differentiating the primitive 

 and medullary sheath from the axis-cylinder ; the latter is very distinct. The 

 non-protoplasmic nature of the envelopes of the fiber is well shown. It is clear 

 that the sheath has at least stood between the axis-cylinder and the stain, or it 

 may have shut out the stain entirely, the latter having perhaps passed in through 

 the end. The stain fades out very gradually in the deeper parts of the fibei . 



I have not attempted to make permanent preparations by this method, it is so 

 easy to make slides that it seems better to work with fresh material. I do not 

 know how long the effect of the stain would last if preparations were kept in 

 glycerine, but I think that it would not be a very permanent preparation. 

 Hamline University. H- L. OSBORN, 



s 



^ 



Stained Axis-cylinder of Fresh Spinal Chord. 



