APPARATUS AND METHODS 241 



The microscope should have a one -inch and perhaps a two -inch 

 eye-piece and two objectives of say |- and i-inch focal lengths. 

 By arranging the laboratory study of the pupils at different times 

 each microscope may be used by three, four, or even more pupils. 



There should be a microtome or section -cutter for use by the 

 class. 



Each pupil should have his own individual tools and bottles of 

 reagents, as follows: 



1 good razor (hollow-ground on one side only), 



1 small scalpel, 



1 pair forceps, 



2 sharp needles mounted in handles (as penholders) (Fig. 19U), 

 1 medicine dropper, 



1 small camel's hair brush, 



A number of slides and cover -glasses. 



Of reagents, stains, and other chemicals, there should be the 

 following: 



Glycerine, 



Ninety-five per cent alcohol, 



Formalin (40 per cent formaldehyde). 



Clearer (made of three parts turpentine and two parts melted 



crystals of carbolic acid), 

 Canada balsam, 

 Ether, 



2 per cent and 5 per cent collodion, 

 Iodine dissolved in water, 



" " " alcohol, 



Hematoxylin, 

 Copper sulfate solution, 

 Potassium hydroxide solution, 

 Fehling's solution (see paragraph 397), 

 Alcanin (henna root in alcohol). 



The two per cent collodion is made of forty-nine parts alcohol, 

 forty-nine parts ether, two parts soluble cotton. This strength is 

 suitable to use in sticking sections to the glass slide to prevent 

 their escape during the staining and clearing process. It need not 

 be used unless desired. Collodion is often useful for imbedding 

 material, as indicated under the head "Imbedding" on page 243. 

 Pupils must exercise great care in using carbolic acid, as it burns 

 the flesh. 



Hematoxylin stain may be obtained of dealers in a condition 



