218 SERIAL SECTION MOUNTING. 



suffices to render the gum insoluble. This layer has the ad- 

 vantage of not staining with the majority of staining fluids; 

 fuchsin and safranin are the only ones that stain it to a 

 harmful degree. In the other anilins, and in carmine or 

 haematoxylin, it does not stain. Watery stains (it is stated) 

 may be used with it. 



331. Born and Wieger's Quince-Mucilage (Zeit. f. wiss. Mik., 

 1885, p. 346). To two volumes of the ordinary pharmaceutical 

 quince-mucilage add one volume of glycerin and a trace of 

 carbolic acid. Spread in a thin layer on a carefully cleaned 

 slide, and arrange the sections on the moist surface. Heat 

 for twenty minutes at a temperature of 30 to 40 C. After 

 removal of the paraffin by turpentine the slide is brought 

 for half an hour into absolute alcohol. You may then mount, 

 or pass through successive alcohols, and stain. Alkaline 

 staining fluids must be avoided, as they soften the mucilage 

 and cause the sections to become detached. 



\. GEAVIS'S Agar-agar (Bull. Soc. Beige de Micr., xv, 1889, p. 72 ; 

 Zeit. f. wiss. Mile., vi, 4, 1889, p. 494). Solution of agar-agar in 1000 

 parts of water, to be used as in last section. The formula seems to me 

 superfluous. 



333. GEAY'S Qelatin Process (The Microscope, ix, 1889, p. 325 ; Journ. 

 Boy. Mic. Soc., 1890, p. 117). Solution of gelatin in 100 parts of water. 

 Use as gum arabic solution, taking care not to melt the paraffin ; let the slide 

 dry spontaneously overnight, and remove the paraffin with a suitable solvent ; 

 remove the solvent with alcohol, and then treat for five minutes with 2 per 

 cent, solution of potassium bichromate to render the gelatin insoluble. Stain 

 as desired, or mount. 



Methods for Watery Sections. 



334. Fol's Gelatin (Foi, Lehrb., p. 132). Four grammes of 

 gelatin are dissolved in 20 c.c. of glacial acetic acid by heating 

 on a water-bath and agitation. To 5 c.c. of the solution add 

 70 c.c. of 70 per cent, alcohol and 1 to 2 c.c. of 5 per cent, 

 aqueous solution of chrome-alum. Pour the mixture on to 

 the slide and allow it to dry. In a few hours the gelatin 

 passes into the insoluble state. It retains, however, the 

 property of swelling and becoming somewhat sticky in pre- 

 sence of water. The slide may then be immersed in water 

 containing the sections, these can be slid into their places, 

 and the whole lifted out ; the sections will be found to be fixed 

 in their places. 



