Journal of Applied Microscopy 



and 



Laboratory Methods 



Volume VI. AUGUST, 1903. Number 8. 



Staining Paraffin Sections on the Slide. 



There are various methods of deaUng with paraffin sections after they have 

 been fastened to the slide. The method formerly employed in our own labora- 

 tory was as follows : The slide was heated until the paraffin melted and then 

 the entire slide was placed in a Stender dish of xylol until the paraffin was 

 removed. To avoid the danger of overheating, the slide was often placed in 

 xylol without previous heating. A very obvious objection to this method is that 

 the xylol soon becomes so saturated with paraffin that it is no longer effective. 

 As a matter of fact, the xylol begins to give inferior results before a dozen slides 

 have been passed through it. After the paraffin had been removed, it was our 

 custom to rinse the slide in absolute alcohol and then successively in 95 per 

 cent., 85 per cent., 70 per cent., 50 per cent., 35 per cent., until an alcohol was 

 reached which had about the same strength as the stain to be used. This 

 method gave good results, but, we believe, is unnecessarily tedious when deal- 

 ing with thin sections in which nearly every cell is cut open on one side or 

 another. 



The method which we are employing at present is by no means new. It is, 

 rather, a modification of a method in vogue as long as fifteen years ago. This 

 method, as we are using it at present, is as follows : 



The slide is heated gently — preferably on the paraffin bath — until the paraf- 

 fin melts. The slide is then immediately flooded with good turpentine, which 

 instantly removes the paraffin. A teaspoonful or, at most, two teaspoonfuls of 

 turpentine is sufficient, if applied immediately, before the paraffin has begun to 

 cool. Even a smaller quantity is sufficient if judiciously applied. We recently 

 put up a lot of 112 slides, nearly all with paraffin ribbons 10/< thick and 50 mm. 

 long. We used only 100 c. c. of xylol and 200 c. c. of alcohol. The paraffin was 

 completely removed. It is best to keep the turpentine in a bottle with a rather 

 small neck, so as to facilitate the pouring. The slide should be held at an angle 

 of about 45° in order that the paraffin may be carried off at once. We do not 

 use the turpentine a second time, but drain it into a waste jar. Since the first 

 two or three cubic centimeters, if applied before the paraffin has begun to cool, 

 will remove almost all of the paraffin, the slide may then be flooded several times 

 and this turpentine may be poured back from the slide into the bottle. Xylol 



(2445) 



