484 AMERICAN JOURNAL OF BOTANY [Vol. 8, 



found to be better for collection than glass jars, as the anthers dried more 

 readily. It was also necessary to keep the anthers spread out, and to place 

 them in a sulphuric-acid desiccator as soon as possible after collection. 



When the anthers are dry, or partially dry, the large, sticky yellow 

 pollen grains easily fall out. They can then be accumulated quickly by 

 placing the anthers on one half of the bottom of a petri dish, moistening 

 the other half with the finger tip, and then when the dish is covered and 

 shaken in a horizontal plane the pollen adheres and heaps up on the mois- 

 tened surface. 



When it was necessary to remove adhering masses of pollen from a dish 

 a glass brush was found better than a camel's hair brush, and for this purpose 

 the glass brush from a Beegee ink eraser was excellent. 



The easiest way of collecting the tiny pollen from many small flowers is 

 by drying the blossoms on large sheets of paper and shaking them through 

 a fine sieve. The anthers usually sift out and the pollen can be separated 

 from the anthers by sifting again through fine silk bolting cloth. (Mimeo- 

 giaph typewriter diaphragm silk is convenient.) The microscope showed, 

 in the case of red maple, that invisible hairs from the flower also sifted 

 through, but the pollen from other plants appeared quite free from foreign 

 particles. 



Wodehouse (1916, p. 430) has suggested an excellent way of collecting 

 large quantities of ragweed pollen. 



The flower heads just coming into bloom are crushed in a mortar with several volumes 

 of carbon tetrachlorid. When strained through muslin the pollen passes through with the 

 CCI4 and can be separated by filtering on filter paper. The pollen is lighter yellow since 

 the CCb probably removed lecithin. 



In collecting pine pollen it was found necessary to gather the staminate 

 cones before they had opened, because later the slightest shaking of the 

 branch scattered a cloud of pollen to the four winds. Cutting off the tassels 

 of corn and allowing them to open indoors, over large sheets of paper, 

 undisturbed by currents of air, gave the largest yield of corn pollen. 



Preliminary Experiments 



These experiments were in two parts: (1) Germination of the pollen 

 grains, and (2) Comparison of the enzyme action of unground, ground, and 

 germinated pollen. The results of these tests showed that the pollen 

 ground with powdered glass was more effective in its enzyme action than 

 either the unground or even the germinated poller. The experiments were 

 made as follows: 



To secure vigorous growthof pollen tubes, Easter lily pollen was ger- 

 minated (1) in tap water, (2) in 3, 5, and 16 percent sugar solution, (3) on 

 agar, and (4) in Knop's solution and modifications. The stock agar recom- 

 mended by Crabill and Reed (1915, p. 2) was used. This contains no 

 carbon-containing nutrient and therefore does not favor bacterial and mold 

 growths, which are exceedingly troublesome. 



