240 TAGG—NOTES ON MUSEUM-METHODS 
not as mounting glasses. With clear glass any background can 
be used and several may be tried from which to select the best. If 
opal or blue glasses are used as the support of the specimen, the 
background becomes part of the preparation, and however 
unsuited it may subsequently prove cannot be varied. This 
becomes a disadvantage where the continued bleaching of a — 
preparation already mounted, or its subsequent darkening, makes 
a change of background desirable. 
Where a white or black background is desired, the back of the 
vessel may be painted the necessary colour. This proves 
effective, and the cost is considerably less than that which the 
employment of blue or opal glass as backgrounds involves. 
DESCRIPTIVE LABELS. 
I. General. 
Long descriptive labels are rarely employed, but in every 
instance an effort is made to indicate concisely the point of bio- 
logical interest the specimen illustrates. 
To facilitate a comparison of the specimens exhibited with the 
descriptions of text books the names of the different organs are 
pointed out. This is done in one or the other of the following 
two ways :—The labels and pointers are attached so that the 
parts named are pointed out upon the specimen itself, or a photo- 
graph or drawing of the specimen is made, and the names of the 
parts are indicated upon this, 
Where the character of the specimen permits its adoption the 
former method presents the advantage that in a direct manner a 
distinguishing name is associated with a given organ. The 
second method, however, where the drawing is made to a certain - 
extent diagrammatic, allows a designated part to be more 
accurately indicated. Examples of the first method are shown in 
Plate III. Details of the way in which the method is carried — 
out follow. 
