56 The Microscope. 



2. Operation. — Place a blank slide on the turn table ; ap- 

 ply a small drop of the staining fluid to the center of the slide 

 and place in it the requisite amount of pollen, and spread it 

 evenly on the glass by placing the sharp point of a teaser in the 

 center of the mass and drawing it gently to one side while the 

 slide is rapidly revolving ; washing away the superfluous stain 

 by dropping clean alcohol on the mass of pollen, using for this 

 purpose a sharp-pointed teaser; wipe away the out-flowing fluid 

 by the use of a small piece of clean cloth rolled neatly and ap- 

 plied to the outer edge of the waste fluid, gradually moving it 

 inward, as the slide revolves, until only a small circle is left 

 covered with pollen ; allow a few moments for the alcohol to 

 thoroughly evaporate from this ; then apply a minute drop of 

 spirits of turpentine, so that the balsam may permeate the mass 

 without enclosing air-bubbles; next apply the balsam, dropping 

 it in a ring around the pollen, and moving it up to the center 

 by placing a small chisel, held upright, to the surface of the 

 slide, at an angle such as to gather it, the balsam, together as 

 the slide revolves ; now lay on the cover-glass and settle it well 

 to place, applying pressure (with a tremulous motion of the 

 hand) sufficient to bring all the pollen grains to a common 

 plane, but yet so as to avoid crushing them ; remove the super- 

 fluous balsam, using the small chisel as before, only setting it 

 so as to throw the balsam away Irom the cover into an outer 

 ring — which operation serves also to accurately center the cov- 

 er-glass; and, lastly, using a wider chisel, take up this ring of 

 balsam, and the slide, furnished with a temporary label , is laid 

 away to cure. 



3. Practical suggestions. 



1st — To secure pollen perfectly clean, the blossom should 

 be plucked just before the unfolding of the flower, placed in a 

 suitable vase with water, and left to expand under bell-glass 

 cover. 



2d — To preserve pollen for future use, tease it out into a 

 watch-glass and leave it for some days, under cover; then store 

 it in small vials properly labeled. Some pollens, however, as 

 the Malvaceae, will not keep in this way ; preserve such in al- 

 cohol, taking care to provide the vials with rubber stoppers to 

 prevent evaporation. 



