114 The Microscope. 



Fob the dentist, as well as for the physician, a knowledge of 

 microscopy is almost indispensable, if success is desired. We are 

 glad to notice in several of our exchanges devoted to dentistry, that 

 this branch of the profession is gradually awakening to the import- 

 ance of the microscope as an aid in the thorough understanding and 

 I^ractice of their specialty. 



Acknowledgments. — From Dr. Brown, London, Ont., catalogue 

 of James Swift & Son, microscopes, etc., London, England. We 

 are glad to see the great improvement in the English stands ; the 

 cumbersome, and to us somewhat clumsy, forms of former years 

 are being remodeled, and many American shapes introduced. From 

 J. D. Beck, Liberty, Pa., slides of vegetable sections stained with 

 echein green. This new stain gives an excellent color, permitting a 

 second stain also. 



TECHNOLOGY. 



Permanent Preparations of Blood. — Amphibian blood. — 

 Spread some fresh blood on a cover-glass upon which has been pre- 

 viously spread some normal fluid. Hold the cover-glass over the 

 open mouth or in the neck of a bottle containing osmic acid for 

 about one minute. The fumes will fix the corpuscles. After the 

 corpuscles are fixed, place on the cover a drop of 75 per cent, gly- 

 cerin containing alum-carmine and fluorescine. Then place the 

 cover on the center of a clean slide, and allow it to settle down by 

 its own weight — do not press it down. The alum-carmine glycerin 

 is prepai'ed : Glycerin, 85 cc, Grenacher's alum-carmine, 10 cc, 

 fluorescine, 5 cc. The fluorescine is made : Fluorescine, ^^ of a 

 gram ; water, 100 cc, chloral hydrate, 2 grams. A fresh solution 

 should be prepared every few weeks. Eosin, ^'o^t^ gram, water, 100 

 cc, may be used instead, of fliiorescine. When the cover-glass has 

 settled, place four drops of shellac cement, (shellac added to 95 per 

 cent, alcohol, set in warm place to dissolve and settle, decant clear 

 fluid, and to each 50 cc. of shellac add 1 cc. of castor oil. Thin at 

 any time by adding 95 per cent, alcohol) at equidistant points 

 around the cover-glass so that half the cement shall be on the slide 

 and half on the cover. Allow the slide to lie flat for a few houi's, so 

 that the cement may dry and fix the cover. Finally wipe away the 

 glycerin around the edge of the cover-glass with a moist cloth, 

 then place the slide on a turn-table nud make a ring around the 

 entire cover-glass. Several thicknesses of the cement should be 



