ON THE STAINING OF SECTIONS 85 



The sections, whether single or in series, are transferred 

 from the alcohol to water, and remain in it until thoroughly 

 saturated, which serves as proof that they are freed from 

 alcohol and from any other fluid that may by chance 

 adhere to them ; after which they are subjected to the action 

 of the selected stain for from two to five minutes to 

 twenty-four hours. The time during which the stain must 

 be allowed to act may, however, be shortened by warming, 

 so far as this can be done without spoiling the tissue. 

 The preparation must now be washed in water as long as 

 any colour comes away from it. The various bleaching 

 agents are next used, and from them the preparation is 

 transferred to water, then to alcohol in order to dehydrate 

 it, and is finally cleared with xylol. It is advisable several 

 times to change the alcohol used for dehydrating. Xylol 

 is employed because it behaves in a completely indifferent 

 manner towards basic aniline colours, whether in nuclei 

 or bacteria, which is not the case with other clearing 

 reagents ; and moreover it evaporates without deposit, 

 never becomes resinous, and consequently does not soil 

 articles with which it comes in contact so much as does 

 oil of cloves.. Besides xylol, oil of turpentine, aniline oil, 

 phenol, oil of bergamot, oil of cedar, oil of origanum, oil of 

 cinnamon, &c., are used. When the preparation has been 

 rendered sufficiently transparent by means of the xylol, it 

 is transferred to a slide and dabbed with blotting-paper, 

 a drop of Canada balsam in xylol is placed on it, and a 

 cover-glass applied. 



TJnna's drying-on process (dry method) . — Sections cut with 

 the freezing microtome are stained in a dilute alcoholic 

 solution of fuchsine, washed in water, laid for a short time 

 in alcohol, double-stained in methyl blue, dabbed with 

 blotting-paper, dried on a slide over the flame, and put up 

 in Canada balsam and xylol. 



