Journal of Applied Microscopy. 393 



Stain from water twelve to twenty-four hours and wash in water. No acid 

 alcohol is needed since the solution does not overstain. 

 Allan Cochineal.— 



Powdered cochineal, 50 gr. 

 Alum, 5 gr. 

 Distilled water, 500 cc. 

 Dissolve the alum in water, add the cochineal, and boil ; evaporate down to 

 two-thirds of the original volume, and filter. Add a few drops of carbolic acid 

 to prevent mould (^Stirling). 



Stain as with alum carmine. A few years ago it was a verj' common practice 

 to stain in bulk in alum cochineal and counterstain on the slide with Bismark 

 brown. 



THE ANILINS. 



Many of the most brilliant and beautiful stains yet discovered belong to this 

 group. These stains are so numerous that we shall not attempt to mention even 

 their names, but shall consider only those which are in most common use by 

 botanists. The followiug formula has proved to be fairly satisfactory for all the 

 anilins mentioned in this account, but other formulas will be given for most of 

 the stains : 



Make a 3 per cent solution of anilin oil in distilled water ; shake well and 

 frequently for a day ; add enough alcohol to make the whole mixture about 20 

 per cent, alcohol; add 1 gr. of cyanin, erythrosin, safranin, gentian violet, etc., to 

 each 100 cc. of this solution. 



The anilins keep well in balsam, but not in glycerine. Xylol is a good clear- 

 ing agent for all of them, but clove oil very much better in case of gentian violet. 

 Unfortunately, some of them do not give permanent stains. Some are acid, 

 some basic, and some neutral. 



The rapidity with which sections must be transferred from one fluid to 

 another makes them more difficult to manage than the haematoxylins or the 

 carmines, but the stains are so valuable that even the beginner should spend 

 most of his time with the anilins. 



Many anilins stain quite deeply in three to twenty minutes, but if the stain 

 washes out during the dehydrating process, stain longer, even ten to thirty 

 hours if necessary. If the stains are made up according to the formula mentioned 

 above, transfer to the stain from 35 per cent, alcohol and from the stain to 35 

 per cent, alcohol if the stain does not wash out too rapidly ; if the stain washes 

 out, try 50 per cent., 70 per cent., 85 per cent., 95 per cent., or even directly to 

 absolute alcohol. It will often be found impracticable to transfer from the stain 

 to alcohols weaker than the <S5 per cent. 



Since the anilins are seldom used as single stains, but almost invariably in 

 combination with other stains, the logical order will be disregarded and the 

 stains will be treated, as they are used, in their most usual combinations. 



Cyanin and Erythrosin. — Stain in cyanin ten to thirty minutes or longer ; 

 rinse quickly in alcohol and then stain thirty seconds to one minute in erythrosin. 

 If the cyanin washes out, stain for an hour, and if it still washes out, omit the 

 rinsing in alcohol and transfer directly from the cyanin to the erythrosin. 



