STAINING AND MOUNTING. 2OI 



with the alcohol and becomes transparent when the 

 xylol is added ; and this transparency is the proof that 

 the steps have been carried out properly. If the section 

 looks opaque when held against a perfectly dark back- 

 ground an additional dose of alcohol must be used, and 

 the xylol applied again. 



Haematoxylin may be used in exactly the same way 

 as haematin in the above process ; it stains more quickly, 

 but does not give quite such beautiful results. 



(2). Gram's method as applied to sections; suitable 

 for sections of diphtheritic membrane, organs containing 

 anthrax bacilli, streptococci, staphylococci, &c. 



1. Xylol, two lots. 



2. Absolute alcohol, two lots. 



3. Water. These steps are always the same with 

 paraffin sections, no matter what stains are to be used 

 subsequently. 



4. Aniline gentian violet five minutes. 



5. Gram's iodine solution three minutes or more. 



6. Absolute alcohol or methylated spirit until no more 

 colour comes out. This step is best carried out as fol- 

 lows : Hold the slide by one end, keeping the fingers 

 clean by using a duster or pair of dissecting forceps, 

 and pour a little spirit on the section ; rock it gently 

 from side to side and notice the clouds of colour which 

 it takes up. After a little time pour off the spirit and 

 add a fresh lot ; repeat the rocking, and pour off again. 

 Do this until the spirit comes away quite clean and 

 does not take up any colour from the section. This 

 may take a long or a short time, and no definite rules 

 can be laid down. 



In some cases decolorisation can be carried out best 

 by the use of clove oil. This is applied when the spirit 

 is wet with absolute alcohol (for it will not mix with 



