CHAPTER V 

 TEMPORARY MOUNTS AND MICROCHEMICAL TESTS 



Before the coming of the microtome and the paraffin method, 

 investigators were forced to develop considerable skill in cutting free- 

 hand sections and in teasing with needles and in making delicate 

 dissections under the simple microscope. Every student should 

 acquire some facility in making mounts for immediate use. The 

 investigator who fancies that he cannot examine a structure until he 

 has a carefully stained microtome section will not make much prog- 

 ress in modern botany. 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 gold size or any good cement. The antheridia and archegonia 



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