156 PREPARATION AND MOUNTING OF DOUBLE STAINING S. 



sold by all druggists as a disinfectant. This result will be 

 accomplished in most cases in about one day. Then, after being 

 thoroughly washed in pure water, the preparations should be 

 placed in a solution of carmine of about the consistence of com- 

 mon carmine ink ; and they may remain in this for a day. Pure 

 carmine will readily dissolve in water with a few drops of aqua- 

 ammonia in it. After being washed in two or three changes of 

 pure water, the objects may now be placed in a somewhat weaker 

 solution of extract of logwood in alum water. A small quantity 

 of alum in the water is sufficient to effect, at least with the aid 

 of heat, the solution of the logwood. This should be filtered, 

 not old at the time of use, and of a strength not more than half 

 that of common writing ink. In this solution the objects may 

 remain from fifteen to thirty minutes, according to the delicacy 

 of the specimens. If the color should appear to be too deep or 

 opaque, it may be partly removed by soaking in pure alum water. 

 Then, after washing again in several waters to remove all trace 

 of the alum, place the objects in alcohol for a short time, and 

 then into a weak solution of aniline blue in alcohol. In this 

 they may remain an hour or two, or until all the parts not 

 previously stained are colored blue. If on trial the blue should 

 appear to be too deep, it may be partially removed by soaking 

 for a time in pure alcohol. It sometimes happens that even 

 aniline blue will riot color all the parts of vegetable substances, 

 such as large glandular or stellate hairs. In this case an immer- 

 sion for a minute or two in a very weak solution of aniline green 

 in alcohol will accomplish the work. Green is the most power- 

 fully absorbent color that I know of; and should be used with 

 caution, as it would soon spoil a staining. 



From alcohol the objects may be removed directly to turpen- 

 tine. I do not like the action of oil of cloves. It shrivels up 

 the tender tissues and gives them the appearance of being 

 burned. Besides, it is not necessary as an intermediary between 

 alcohol and turpentine. After a day's immersion in turpentine 

 the preparations will be ready for mounting in Canada balsam. 

 Vegetable preparations have quite an appreciable thickness, and 

 unless some special care is taken of them after being mounted in 

 balsam, it will be found that air will quite often work in under 



