MICROSCOPICAL TECHNIQUE. 107 



minute or two ; they are then arranged on a slide, and the super- 

 fluous alcohol drained off by tipping the slide, after which sulphu- 

 ric ether-vapour is poured over them from a bottle partly filled 

 with liquid ether. Under this treatment the celloidin softens and 

 becomes transparent. The slide may then be immersed in 80 per 

 cent, alcohol, and the section afterwards stained, anhydrated, and 

 mounted in balsam by the usual process, as the ether treatment 

 serves to fasten the sections firmly to the slide. — -Jour rial Recon- 

 structives. 



Styrax for Mounting.— Sty rax is being recommended in Eng- 

 land and America as a mounting medium in certain cases. As 

 the balsam of the shops is always full of dirt and impurities, it 

 requires preparation before it can be used in microscopy. The 

 best plan is to to dissolve and filter it. To do this, dissolve a 

 portion of the styrax in sufficient benzol to make a liquid of a thin 

 syrupy consistence, and filter through two thicknesses of Swedish 

 filter-paper. Use a large filtering-funnel, fitted with a cap to 

 prevent evaporation, and let the filtering-paper reach not much 

 more than midway up the sides. Should the medium become too 

 thick to pass through, add more benzol. The product will be too 

 thin to use at once, and may be set aside, properly protected from 

 dust, until sufficient benzol evaporates. 



Wheat and Rye Starch.*— E. Guenez points out that these 

 starches possess very similar characters, and it is difficult at times 

 to say decidedly that a given sample consists of one rather than 

 the other. To distinguish the two kinds, he recommends that a 

 little of the material be mounted in water for examination with 

 the microscope. The wheat-starch will then be seen to contain 

 comparatively few split grains, which possess an isolated fracture 

 situated near the edge or proceeding from the centre to the circum- 

 ference. In the case of rye starch the split grains are more nume- 

 rous, and possess a star-shaped fracture with three or four branches, 

 apparently originating in the centre of the grain and rarely reach- 

 ing the edge. Some grains may also be found which have only a 



*Bull. de PharjH. de Bordeaux, xxxiv., 289, in Pharm. /ourn., Nov. 3, 1894, 



P- 356. 



