49 



the sections freely. Cautiously and slowly warm the slide over a 

 small flame, as that of an alcohol lamp, or upon a metal warming table 

 until the sections begin to spread and straighten out. When the 

 wrinkles have entirely disappeared, allow the water to cool and then 

 drain it off, retaining the sections in position. The slide should now 

 stand 2 to 3 hours or better over night when the water beneath the 

 sections having evaporated they will have been brought close to the 

 albumen fixative. They are now ready for the remaining steps. 

 Melt the paraffin by warming the slide over a low flame and place it 

 in xylene ( 143). 



139. Albumin fixative and Heat. If the sections are free 

 from wrinkles or with few wrinkles that can be easily "ironed out," 

 place the sections in position upon a slide prepared with albumin 

 fixative as above, and with a clean finger press the section into the 

 albumin fixative beginning at one edge of the section and by a rolling 

 motion of the finger, ironing out any wrinkles that there may be. 

 It is well to look upon the reverse side of the slide to see if the section 

 really adheres to the albumen fixative, as in some cases it does not. 

 Heat the slide gently and slowly over a small flame until the paraffin 

 melts and begins to run away from the specimen. Keep the paraffin 

 just melted for a minute or so, and then transfer to the xylene. 

 Should the paraffin section not adhere to the albumin fixative when 

 well pressed down, it can in many cases be made to do so by briskly 

 rubbing the reverse side of the slide with a woolen or silk cloth. 



140. J4% Celloidin (collodion). The adhesion of sections 

 that are particularly valuable or relatively thick may be ensured by 

 treating them with %% celloidin, as follows : Fasten the sections to 

 the slide by either of the above methods, remove the paraffin by 

 xylene ( 143), and then after draining off the xylene from the slide, 

 10 to 13 seconds, it is put into a bottle containing J4% celloidin. In 

 a minute or more the celloidin displaces the xylene and penetrates 

 the sections. The slide is removed, allowed to drain for half a minute 

 and then put into a jar of 67% alcohol which sets the celloidin [17]. 

 It is now ready for the staining processes ( 144 ). 



PRELIMINARY STEPS. 



141. These are somewhat different for paraffin and celloidin 

 sections. In the case of the former, it is necessary to remove the 

 paraffin by means of a solvent (e. g., xylene), remove the paraffin 



