57 



(1) Mode of fixation (detail) . 



(2) Imbedding method. 



(3) Stains employed (detail). 



(4) Mounting medium (generally not necessary). 



(5) Special purpose of the preparation. 



A catalog giving the full data of the specimen, age, condition 

 of the animal, mode of preparation in detail, special points illus- 

 trated, etc., is valuable particularly in special investigations and 

 with standard specimens. 



Paper labels are very convenient but possess the disadvantage that they are 

 very apt to come off. In this laboratory it is the custom to label permanent 

 preparations by means of a writing diamond with the record number at least. 



166. A carbon ink label written upon the slide itself is fairly durable and 

 may be made as follows: First coat the end of the slide with a thin solution of 

 balsam (xylene or benzene), and permit this to dry thoroughly. Upon this surface 

 it is possible to write neatly with carbon ink and after the ink is dry a second coat- 

 ing of the thin balsam or of shellac may be given. This method is recommended. 



SLIDES AND COVERS. 



The slides and cover-glasses used in histological work are often 

 slightly greasy and should be cleaned before using. After they are 

 cleaned they should be handled by the edges only, or with forceps. 



167. Cleaning Slides. For ordinary work it is enough to 

 wipe the slides out of clean water to which about 5% ammonia has 

 been added. A clean glass towel free from lint should be used and 

 after the slides are cleaned they should be stored in covered glass 

 jars away from the dust. 



168. Cleaning Cover-glasses. Place them in 95% alcohol 

 to which 1% of hydrochloric acid has been added. A clean, soft 

 cloth such as an old linen handkerchief, gauze, etc., should be used 

 for wiping them. In wiping a cover-glass "grasp it by the edge with 

 the left thumb and index. Cover the right thumb and index with 

 the cleaning cloth; grasp the cover between the thumb and index 

 and rub the surfaces keeping the thumb and index well opposed on 

 directly opposite faces of the cover so that no strain will come upon 

 it, otherwise the cover is liable to be broken." (Gage, 17). 



Cover-glasses when cleaned should be stored in covered glass 

 boxes, or in Petrie dishes. 



169. Cleaning Mixture for Glass. For special purposes, such as when the 

 slide or cover-glass is to be used in the preparation of blood smears, the cleaning 



