158 The Preparation of Microscope Slides 



tive Use and Proper Care of the Microtome," which lists many sugges- 

 tions beyond those here given. 



Staining and Mounting Sections. Assuming that all the difficulties men- 

 tioned in the last section have been overcome and that one now has a 

 series of slides bearing dried consecutive ribbons, the next thing to be 

 done is to remove the paraffin in order that they may be stained. It is 

 conventional, although probably not necessary, to warm each slide over a 

 flame (holding it as shown in Fig. 117) until the paraffin is melted 



2^> 



M^r 



C 



I i '■ 



ill 



■*i; 



if A w"H '$&&■■ ■■• 



\Y - 



Fig. 125. Starting a slide through the reagent series. 



thoroughly. Then the slide is dropped, as shown in Fig. 125, into a jar 

 containing xylene, benzene, or some other suitable paraffin solvent. 



It is necessary through the subsequent proceedings to be able to recog- 

 nize instantly that side of the slide on which the section lies. This is not 

 nearly so easy as it sounds, and a lot of good slides have been lost by 

 having the sections rubbed off them. The simplest thing to do is to incline 

 the slide at such an angle to the light that, if the section is on top, a reflec- 

 tion of the section is seen on the lower side of the slide. A diamond scratch 

 placed in the corner is of little use because it becomes invisible when the 

 slide is in xylene. The greatest care should be taken to remove all the wax 

 from the slide before proceeding further, and it is usually a wise precau- 

 tion to have two successive jars of xylene, passing the second jar to the 

 position of the first and replacing it with fresh xylene after about 10 or 



