102 



THE AMERICAN MONTHLY 



[June, 



in large pieces, which may be stained 

 and mounted in balsam, or else 



Fig. 15.— Ground Tea. 



mounted in dilute glycerin without 

 staining, as we prefer. 



Another method of making the 

 structure of leaves visible under the 

 microscope may also be employed in 

 these examinations. Place a portion 

 of the leaf on a slip of glass, spread 

 out flat, cover it with thin glass, and 

 place a coin on top for a weight. 

 Moisten it with a few drops of an al- 

 kaline solution of potassic permanga- 

 nate and heat carefully to boiling. 

 Wash with water and then let a few 

 drops of hydrochloric acid flow under 

 the cover-glass, to dissolve the oxide 

 of inanganese -which v^^as formed in 

 the tissues by the previous boiling. 

 Then wash again with water. The 

 protoplasm is thus destroyed, and 

 only the more firm cellulose mem- 

 branes remain, showing perfectly the 

 structure of the leaf. 



Still another method is to carbo- 

 nize the leaf by heating it, covered 

 with thin glass, weighted as before, on 

 a strip of platinum. The ash thus re- 

 maining retains the form of the leaf. 



To detect the facing on the leaves 

 it is only necessary to examine them 

 dry by reflected light, when the mi- 

 nute particles w^ill be readily seen 

 under a low-power. By boiling the 

 leaves in water the particles of mi- 

 eral matter are detached, and on 

 standing will sink to the bottom as a 

 fine sediment, which may be ex- 

 amined. 



Microscopical Exhibits at the New 

 Orleans Exposition. 



BY L. W. CHANEY, JR. 



The display of microscopical appa- 

 ratus which the exposition called forth 

 was not a little disappointing — not in 

 the quality of the exhibit, but in its 

 extent. But two firms made exhibits 

 of microscopes and apparatus of suf- 

 ficient importance to challenge atten- 

 tion. There may have been others, 

 but four weeks of diligent search 

 failed to reveal them. The firms re- 

 ferred to were the Bausch and Lomb 

 Optical Company and the Mcintosh 

 Galvanic Company. The first-men- 

 tioned doubtless manufacture the full- 

 est line of optical goods of any firm 

 in this country. Their exhibit, al- 

 though unfortunately placed and too 

 crowded to show to the best advan- 

 tage, was of great interest and excel- 

 lence. Their stands ai'e as a whole 

 good representatives of what has been 

 called the American model. They 

 have neither the clumsy complication 

 of some of the large English models 

 nor the severe plainness chai-acteristic 

 of the Continental forms. There is 

 doubtless an evolutionary process go- 

 ing on in this matter by which we are 

 attaining the form best suited to our 

 needs. Their ' universal ' stand par- 

 ticularly attracted attention. It seems 

 in many respects to deserve its name. 

 It may be reduced to a simplicity 

 which would almost command the 

 approval of the admirer of German 

 style, and at the same time is capable 

 of development in various ways which 

 add much to the ease and rapidity of 

 manipulation. The glass stage and 

 slide-carrier, which may be applied 

 to this and other stands, is an admira- 

 ble contrivance. It has one marked 

 advantage over the forms held down 

 by ivory points, in that it maintains 

 its position much better when the in- 

 strument is placed horizontal. 



At the time of my visit they did not 

 have a full display of objectives, the 

 homogeneous-immersion series not 

 being represented. As they claim 



