274 James Homer Wright. 



The Method 



The material should be obtained immediately after death or 

 taken from the living animal. 



For fixation methyl alcohol, formaldehyde, or a saturated 

 solution of mercuric chloride in a 0.9 per cent solution of sodium 

 chloride, may be used. Methyl alcohol is not now recommended 

 for fixation. Formaldehyde should not be allowed to act longer 

 than forty-eight hours. The method is not applicable to material 

 fixed in Zenker's fluid. 



The tissue is dehydrated by alcohol followed by acetone, 

 cleared in thick oil of cedar followed by xylol, and imbedded in 

 paraffin. 



The sections should not be more than 4j« in thickness. 



Crystals of corrosive sublimate in the sections are to be removed 

 by treatment with Gram's solution of iodine and alcohol. 



The sections are stained while affixed to the slide by Meyer's 

 glycerine-albumin mixture. 



The staining fluid and the mode of its preparation are described 

 below. 



The staining, clearing and mounting is carried out as follows : 



1. Equal parts of the staining fluid and distilled water are 

 mixed in a small wine glass and immediately poured on to the slide. 

 The measuring is conveniently done by means of a small pipette 

 provided with a rubber bulb. At least 2 cc. of the freshly diluted 

 staining fluid are thus spread out over the slide, which should be 

 supported upon some object in such a way as to prevent the fluid 

 from running off. The spreading out of the fluid in a layer is 

 important because it facilitates the evaporation of the alcohol 

 whereby the staining elements slowly precipitate out of solution 

 and, while doing so, stain the tissue elements. This precipitate 

 appears as a yellowish metallic scum which slowly forms on the 

 surface of the mixture. The diluted staining fluid is allowed to 

 act for about ten minutes when the preparation is immediately 

 washed in water. The exact time required for the best results has 

 to be determined for each batch of the staining fluid. The proper 

 staining of the preparation may be judged by examining it by a 



