226 THE AMERICAN MONTHLY [July 



comparisons is dug* out of or cut otf the herbarium speci- 

 men as it is needed from time to time and placed 

 loosely under the lens for examination, and after it has 

 served the-purpose of the moment is brushed aside and 

 lost or at best preserved in packets upon the sheet with 

 the specimen from which it was taken. This method is 

 mussy and eventually impairs the mounted specimens of 

 an herbarium, and where there are rnany workers it is 

 not economical of time. To avoid this is quite practica- 

 ble through the preservation of all such materials dry in 

 cells upon glass slips as opaque mounts for the micro- 

 scope. The cells are built by gluing to the glass slips 

 brass rings, and the specimens are enclosed by cement- 

 ing to the top of this ring the ordinary circular cover 

 glass. The method of building this form of cell was 

 suggested by Dr. Griffiths some years ago and is quite 

 familiar. A cell of this form will not accommodate 

 leaves and some other plant structure as well as another 

 form of cell, which is made by gluing a rectangular 

 frame cut from cardboard to the glass slip. A cell of 

 this construction Avill contain small leaves entire or the 

 tip and basal portions of the larger leaves, which can be 

 viewed from either side. A cell of this type must be 

 enclosed by a rectangular cover-glass. A supply of slips 

 upon which cells of various sizes have been built, may 

 easily be kept on hand, and whenever it becomes neces- 

 sary to remove from an herbarium specimen material for 

 examination, it may be placed in a cell in manner best 

 adai)ted for its display, labeled, and you have at once, 

 at very small expense, a slide of vegetable material 

 which will be ready for use at any future time; and, if 

 such a collection of slides is properly classified and 

 arranged, it forms u working adjunct to the herbarium 

 of much value, and, besides, provides one constantly 

 with available material for numbers of demonstrations 

 in botanical work. 



