1893.] THE MICKOSCOPE. 59 



third add twice its bulk of alcohol and ether in equal parts. 

 Take the tissue out of the ether and put into the thinnest of the 

 above three solutions for a few hours, then transfer to the thicker 

 one for three or four hours, and, lastly, to the thickest for a day : 

 take out and dry in the air, and place in spirit until quite hard and 

 opaque. It can now be easily cut. 



The sections will be much more easily examined if they are 

 stained one or more colors, and if they are to be stained they 

 must usually be first bleached. First, wash out the spirit by 

 placing in water, and then bleach by soaking in liquor sodce chlo- 

 rinatcE for from two to ten hours. When all the color has dis- 

 appeared from the sections, wash them in water three or four 

 times at least. They can now be kept in spirit until required. 



Tudson's dves were at one time used for staining- these sections, 

 but now specially prepared stains are more generally used, which 

 can be bought, or made if more than a very small quantity is 

 required. 



The spirit should be first washed out of the specimen. It 

 should then be immersed in the staining fluid for from three to 

 ten minutes, and washed in spirit for from ten to fifteen minutes. 

 Lastly, the section, w T hich now presents a dull appearance, is 

 cleared by placing in some clove oil until it sticks in (usually 

 about five minutes) ; it will then be found to be quite clear, and 

 ready for mounting in Canada balsam, or, more conveniently, in 

 a mixture of Canada balsam and one-fifth its bulk of pure turpen- 

 tine. 



The brightness of a section stained with borax-carmine is in- 

 creased by placing it in a mixture of spirit and one-sixth its bulk 

 of hydrochloric acid for a minute or so. The acid must after- 

 ward, of course, be thoroughly washed out. 



If a section is over-stained it may be remedied by placing it in 

 a dilute spirituous solution of hydrochloric acid, or dilute aqueous 

 solution of acetic acid, according to the stain used. 



Double staining is accomplished by using alkaline and acid so- 

 lutions respectively : for example, green and red, by first placing 

 in an acid green solution, washing with water and then placing 

 in borax-carmine solution ; then wash in spirit, and ciear in olive 

 oil. 



Clove oil is a very good clearing medium and a very good 

 vehicle in which to preserve the sections until required for 

 mounting, if it is intended to mount them in Canada balsam. If 

 a specimen is stained before it is sectionized it must, of course, 

 be left in the stain hours, and perhaps days, instead of min- 

 utes. This is only done with soft tissues, such as ovaries, which 

 should be gathered before they are quite ripe. Fresh stems 

 should not be more than three years old as a general rule. 



Sections must not be bleached where there are cystolithes or 



