The Mickoscope. 273 



and syrup, carefully dried with a soft, clean cloth; then placed in 

 B. P. mucilage, until the surface is thoroughly saturated, (ten min- 

 utes is quite sufficient for this), after which it is transferred to the 

 freezing plate, on which a very thin layer of gum has been laid. The 

 section becomes fixed immediately. It must then from time to time 

 be carefully banked up with gum, the tin freezing box being placed 

 over it during the intervals. When nearly frozen, take a long thin 

 knife and pare the tissue down to the level of the rails. Now pre- 

 pare a large, clean, white, flat dish, fill with slightly warm distilled 

 water, to which a little syrup may be added (specially if the tissue is 

 at all brittle) and place it in front of the tub, about an inch below 

 the level of the sections, so as just to clear the plane. In this lay the 

 sheet of glass which is to serve as the cover-glass. This should be 

 considerably larger than the section. The glass, I find, best suited 

 for the purpose is thin rolled plate, which is to be obtained only 

 from Messrs. Chance, Birmingham, Eng. Take the first complete 

 section, if thin enough, spread out with the aid of a camel-hair pen- 

 cil on the glass, on which it is carefully removed from the water and 

 transferred to a second vessel containing distilled water, where it is 

 allowed to stand for a few hours in order that all the mucilage and 

 sugar may be thoroughly washed out. The sections may be mounted 

 either as they are, unstained, or they may be stained with alum- 

 carmine, picro-carmine, or ordinary ammonia-carmine; but the two 

 former are, in my opinion, the best. 



In staining with picro-carmine, a rapid staining on the slide, 

 with no after- washing except around the section, is best. For the 

 alum-carmine staining, the best method is to transfer the cover-glass 

 with its section to the staining fluid, where it may be left for a 

 night. It is then put back into distilled water, and is there thor- 

 oughly washed in order that all alum crystals may be removed. In 

 order to clear up some of the unstained sections, Hamilton's liquor 

 potassse method may be used. After the sections have been thor- 

 oughly washed, he pours over the surface with a pipette a strong 

 solution of liquor potassse and water. Strength of 1-4 gives the 

 best results. When thoroughly cleared up, the section may be 

 mounted. To imbed and mount, take a quantity of gelatin 

 (Nelson's or Cox & Coignet's), wash well and cover with a 

 saturated and filtered solution of salicylic acid. Allow it to 

 soak all night, so that a considerable quantity of water may be 

 absorbed. Pour ofP superfluous water and heat over a water-bath 

 until the whole is thoroughly melted. Add one part by measure of 

 this to two parts of glycerin ; heat over a water-bath, stirring 



