78 Nervous Structures. 



stained with logwood, which shows up the structural 

 elements better than any other stain. 



Human brain is best hardened in 2 per cent, solution 

 of bichromate of potash, page 13 ; it must be well 

 washed until no more coltor comes away, before sections 

 are cut. This method is equally applicable to all large 

 brains. 



Large sections of brain may be cut with the micro- 

 tome, but for Histological work small sections will be 

 found to show all that is required. It is a compara- 

 atively easy matter to cut a large section, but to pass 

 this section through all the different re-agents and 

 finally to get it laid out smoothly on the slide, without 

 tearing, is a very difficult matter indeed. 



Bichromate of ammonia (p. 13), may be used in the 

 same manner as bichromate of potash, for all nervous 

 structures. 



To show the neuroglia of the brain, it must be cut in 

 small pieces and hardened in the ordinary chromic acid 

 mixture. 



PACINIAN COKPUSCLES. 



These are best seen in the meso-rectum of cat, where 

 they are visible to the naked eye as oval bead-like 

 bodies. Cut out a portion of the meso-rectum and 

 spread it on a flat piece of cork, fasten it at the sides 

 by a few pins, and invert the cork in a vessel containing 

 a 2 per cent, solution of bichromate of potash ; let it re- 

 main in this for a few days, then cut it into small pieces 

 and wash well, place them in a very dilute solution of log- 

 wood, one drop to a watch glass of distilled water will 



