CHAPTER V 
TEMPORARY MOUNTS AND MICROCHEMICAL TESTS 
Skill in making freehand sections, without any microtome, and 
in teasing with needles and in making delicate dissections under 
the simple microscope are absolutely necessary in any investigation 
dealing with the structure and development of plants. Preliminary 
study with the aid of such methods not only gives a broader view of 
structures in all dimensions and helps the interpretation of stained 
microtome preparations, but is necessary in determining whether 
material is worth all the labor of making permanent mounts. That 
particular class of temporary mounts intended only for chemical 
tests is considered separately in the second part of this chapter. 
TEMPORARY MOUNTS 
A preliminary examination of almost any botanical material 
may be made without any fixing, imbedding, or staining. If a little 
starch be scraped from a potato, and a small drop of water and a 
cover-glass be added, a very good view will be obtained, and if a 
small drop of iodine solution be allowed to run under the cover, the 
preparation, while it lasts, is better than some permanent mounts. 
The unicellular and filamentous algae can be studied quite satis¬ 
factorily from such mounts. The protonema of mosses and the 
prothallia of ferns should be studied in this way, even if a later 
study from sections is intended. The addition of a little iodine 
identifies the starch and makes the nucleus more plainly visible. 
If the top of a moss capsule be cut off at the level of the annulus, a 
beautiful view of the peristome may be obtained by simply mounting 
in a drop of water, or, in a case like this where no collapse is to be 
anticipated, the object may be mounted in a small drop of glycerin— 
just enough to come to the edge of the cover without oozing out 
beyond—and the preparation may be made permanent by sealing 
with balsam, gold size, or any good cement. The antheridia and 
archegonia of mosses may be examined if the surrounding leaves are 
carefully teased away with needles. Freehand sectioning with a sharp 
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