Water Glass as a Medium for Permanently Mounting 
Dissections of Herbarium Material 
E. QuIsuMBING 
During the past four years I have given some attention to the 
problem of selecting a simple, permanent, and satisfactory method 
of preserving dissections of flowers in the herbarium in connec- 
tion with taxonomic work. The methods generally used are more 
or less unsatisfactory, partly because of the involved technique in 
mounting material in the media commonly used, such as Canada 
balsam, Venetian turpentine, glycerine, glycerine jelly, etc., and 
partly because of the unsatisfactory nature of the mounting me- 
dium, particularly glycerine and glycerine jelly, as to permanency. 
The common herbarium practice is to boil the flowers or fruits 
selected for dissection in water, or in water with a little glycerine 
added. After dissection and examination the fragments are nor- 
mally placed in small packets attached to the sheets. This in- 
volves considerable breakage, more or less loss of material, and 
furthermore, if reéxamination of the dissections is necessary, as 
is frequently the case, the material must be softened again; in 
€ majority of cases the taxonomist will remove and dissect addi- 
tional flowers or fruits rather than take the trouble to soften the 
Original dissections. F requently, where scanty material is avail- 
able, this results in the ultimate destruction of essential parts, and 
one will find important historical specimens from which all or 
most of the flowers have thus been detached, leaving little or 
nothing for reéxamination. In those cases where but scanty 
material is available it is essential that every effort be made to 
Preserve the parts used for dissection. 
In some herbaria the dissections are attached in a smear of 
um arabic, or some other adhesive, either to the herbarium sheet 
itself, or to small pieces of stiff paper or cardboard, which in turn 
are attached to the sheet or placed in a packet. This method is 
distinctly unsatisfactory for several reasons. In many cases 
Ne adhesive cracks; in humid climates it is apt to mold; some- 
times insects are attracted by the paste and occasionally destroy 
th the paste and dissections; and there is frequently breakage 
or loss of dissections. Material so mounted is distinctly unsatis- 
i actory for reéxamination unless again moistened, and moisten- 
Ng is often difficult, The greatest objection is that the opaque- 
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