LABORATORY DIRECTIONS. 463 



10. Xylol creosote (beechwood creosote, 20 



parts; xylol, 80 parts). 



1 1 . Mount in Canada balsam and cover. 

 The sections must become perfectly transparent in 

 the xylol creosote. If they are cloudy or milky, 

 water is present ; and the sections must be returned 

 to alcohol, 95%, and the process repeated. Sections 

 that curl should be flattened out when lifted out of 

 95% alcohol, because in this the sections are soft. 

 In xylol or in water the sections are hard. 



9. Staining Paraffin Sections. Since the paraffin 

 has to be removed the sections first have to be fixed 

 to the glass slide or cover glass. 



(1) Spread fixative on slide. Albumin fixative 

 consists of egg albumin and glycerin, equal parts. A 

 very thin spread is all that is necessary. Schaellin- 

 baum fixative consists of clove oil 4 parts and thin 

 celloidin i part. A thicker spread of this is used. 



(2) Place section upon slide and heat gently. 



(3) Xylol or turpentine to remove the paraffin. 



(4) Absolute alcohol to remove the oil. 



(5) Alcohol, 95%. 



Stain on the slide, or immerse the whole slide in the 

 stain, following directions as for celloidin sections. 



Stain in bulk before imbedding in paraffin when- 

 ever this is possible, as then the sections may 

 be mounted from xylol directly into balsam. An 

 excellent way to get sections smooth is to float them 

 on warm water not so warm as to melt the paraffin 

 an4 then lift them out upon the glass slide. 

 Decant surplus water and put away for twenty-four 

 hours to dry. Next day remove paraffin with xylol 

 and stain according to above directions. 



