134 On Staining and Mounting Wood Sections, By M. II. Stiles. 



generally be sufficient preparation for the section machine. After 

 cutting, soak the sections in water containing about 10 per cent, of 

 spirit until the tissue is freed from air, or, if convenient, put them 

 for a few hours under the exhausted receiver of an air-pump. 



In order to get the best results with staining liquids, the sec- 

 tions, if at all dark-coloured, should be bleached. A very cheap and 

 effective bleaching liquid may be made by mixing \ ounce of chloride 

 of lime with a pint of water, shaking occasionally for an hour, and 

 after allowing the sediment to subside, decanting the clear solution. 

 Unless the tissue be very dark and dense, from six to twelve hours' 

 immersion in this liquid will be sufficient. It is not advisable to 

 use a stronger solution, and in any case the process of bleaching 

 must be watched and arrested when complete, or the objects may 

 become too tender to bear the subsequent preparation for mounting. 

 After pouring off the bleaching solution, wash the sections by soak- 

 ing them for at least twelve hours in water, changing frequently, 

 and finishing with distilled or filtered rain water.* 



Previous to staining they should be placed in spirit for about an 

 hour. A small beaker is a convenient vessel for this and the sub- 

 sequent operations, and to avoid injuring the sections, they need not 

 be removed from this beaker until ready for mounting. 



Of the aniline colours in general use, magenta and blue give 

 the most pleasing results. The magenta staining liquid is made 

 by dissolving 1 grain of the finest cake or crystal magenta in 

 2 ounces of spirit ; the blue dye is prepared by dissolving ^ grain 

 of pure soluble blue in 1 drachm of distilled water, then adding 

 10 m'inims of dilute nitric acid and sufficient spirit to measure 

 2 ounces. It is a convenient plan to prepare stock solutions eight 

 times the strength given here, and dilute them when wanted. 



The time required to stain different tissues varies, so that no 

 special period can be fixed: from twenty to forty minutes will 

 generally be sufficient, but the objects should be examined every 

 few minutes to guard against their becoming too deeply coloured. 

 After pouring oS" the staining solution, wash the sections three or 

 four times with spirit, drain them for a few minutes by inverting 

 the beaker containing them over a piece of blotting paper, and then 

 soak them in oil of cajuput for an hour : at the end of this time 

 remove the oil, drain on blotting paper as before, then immerse the 

 sections in turpentine ; after they have remained in this liquid for 

 an hour remove it and add fresh. The sections are now ready for 

 mounting in balsam or dammar, which operation should not be 

 long delayed. 



* The elimination of the clilorine will be much facilitated by placing the 

 sections, after removal from the bleaching liquid, in a solution of hyposrdphite 

 of soda (1 drachm to 4 ounces of water) fur an hour ami then washing as 

 directed. 



