The Microscope. 151 



Methods of Preparing Cartilage. — Cartilage must be prepared 

 in several ways, as no one preparation can show all the points of 

 interest to be seen. The piece must first be placed in a saturated 

 solution of picric acid for 48 hours. Hyaline cartilage may be 

 taken from the trachae, the cartilage of the rib (costal) or from the 

 end of one of the long bones before ossification has taken place. 

 Yellow fibre cartilage may be obtained from the epiglottis of an ox, 

 and should be immediately washed and placed in a saturated 

 solution of picric acid for 48 hours, then washed, either cut and 

 mounted or placed in 95 per cent, alcohol for future u.se. White 

 fibro- cartilage is best obtained from cutting away the intervertebral 

 disc with the bone and placed together in equal parts of chromic 

 and nitric acid until a needle can be thrust through the bone, then 

 wash away all the acid and place in spirit until required. Hyaline 

 cartilage stained in logwood shows the matrix and cells. Costal 

 cartilage from a kitten stained in osmic acid 1 per cent, for 12 hours. 

 This stains the corpuscles a deeper yellow than the matrix. Osmic 

 acid, iodine solution, silver- nitrate solution, carmine and eosin are all 

 required in the staining and elaborate study of cartilage. When 

 the cartilage is of adult tissue it should first be decalcified. — Amer. 

 Postal-Micro. Club. 



Mounting Diatoms Without Heat. — Mr. K. M. Cunningham, of 

 Mobile, Ala., sends the following method : In mounting diatoms a 

 minute drop of the containing fluid is placed on a cover and allowed 

 to dry in the air, protected from dust. This prevents the un- 

 sightly matting which occurs when heat is employed. When the 

 cover preparation is thoroughly dry, a very fluid drop of chloroform 

 balsam is placed on it. This in turn is allowed to dry, and the cover 

 then placed on a minute drop of the balsam on the slide. We have 

 tried this method and cordially recommend it, when time is no object. 



Finishing Varnishes for White and Colored Rings. — Mr. C. 

 Wellington, of Jackson, Mich., prepares excellent varnishes, the 

 formulae for which, although well-known, will bear repeating. These 

 are made by tritui'ating the various colors with the vehicle in a 

 mortar. It will be found best, after preparing each color, to place 

 them in saucers such as are used by artists ; the benzole then 

 evaporates, and the color can be taken up in a brush as required, by 

 simple moistening it with benzole. The vehicle : gum dammar, 3 

 oz. ; gum mastic, 1 oz. ; benzole, 6 oz. The colors : White, oxide 

 of zinc ; blue, ultramarine ; red, carmine ; black, lamp-black : 

 green, verdigris ; yellow, chrome-yellow ; gold, gold-bronze. 



