On Staining and Mounting V/oocl Sections. By M. H. Stiles. 135 



Dr, Beatty has recommended the staining of sections of wood 

 in two colours. This may be accomjolished by macerating for 

 twenty to thirty minntes in the magenta solution, washing witli 

 spirit, then treating with the blue dye for five to ten minutes, well 

 washing, and afterwards soaking in oil of cajuput and lastly in 

 turpentine. 



The two kinds of tissue — vascular and cellular — peem to have 

 a special selective power with regard to the colours employed ; the 

 cellular more readily taking blue than red, and the vascular to a 

 great extent retaining red when subsequently treated for a short 

 time with blue. Thus a transverse section of wood carefully 

 double-stained will have the vessels, wood cells, and liber tissue 

 more or less red, and the pith, medullary rays, and cellular tissue 

 of the bark blue or violet. 



Independently of stained wood sections, this process of pre- 

 paring objects for mounting in balsam or dammar admits of exten- 

 sive application. It is a difiicult matter to thoroughly dry a deli- 

 cate tissue without injuring and in some cases almost obliteratmg 

 its structure, and it is well known that an imperfectly dried speci- 

 men will not make a satisfactory object when mounted in balsam 

 or dammar. 



By the method here indicated, tissues far too delicate to bear the 

 ordinary preparation for mounting in these media, can be success- 

 fully treated, and a good result obtained. 



I believe the use of oil of cajuput for this purpose is entirely 

 new, and, as the oil is not very generally known, the following notice 

 of its source and properties may be interesting. Oil of cajuput is 

 distilled from the leaves of Melaleuca minor, a plant growing in the 

 Molucca Islands. It is very limpid, of a pale bluish-green colour, 

 and has a strong but not unpleasant odour. It is miscible with 

 rectified spirit* and turpentine in all proportions. This oil is 

 superior to the oils of cloves and aniseed in being more limpid, 

 considerably cheaper, and in not staining the tissue treated with it 

 as does oil of cloves. 



♦ Throughout this process of staining, &c., an efficient sul)stitute for rectified 

 spirit will bo found in methylated spirit that had been digested with animal 

 charcoal and carbonate of magnesia, | ounce of each to the pint, for two or three 

 hours, and then liltered. 



VOL. XV. 



