STUDIES IN POLLEN, WITH SPECIAL REFERENCE TO LONGEVITY 757 
hundred and seventy-seven hours eld, fertilized successfully, and sweet- 
pea pollen fertilized after twenty-three days. 
Kellerman (1915) shipped Citrus pollen from Florida to Japan, using 
four methods of storage: (1) in cork-stoppered vials, (2) in cotton-stop- 
_pered vials, (3) anthers in glass tubes exhausted to 10 millimeters pressure, 
and (4) anthers in dried glass tubes exhausted to 0.5 millimeter pressure. 
During shipment, which covered a period of from four to six weeks, the 
pollen was kept at a temperature as near 10°C. as possible. Both the third 
and fourth methods were successful, but the fourth was the more so. 
Andronescu (1915) worked on the longevity of corn pollen. Corn 
pollen kept in a dry oven, at 42° C., was killed in twenty minutes, while 
in a saturated atmosphere, under the. same conditions, there was 32 per 
cent of germination. Pollen exposed in the laboratory died in two hours; 
uncovered, out of doors, it lived for four hours; in 60-per-cent moisture, 
for six hours; in 90-per-cent moisture, for forty-eight hours. Pollen in 
sealed tubes lived for twenty-four hours. 
McCluer (1892), also working with corn pollen, found that if kept dry 
it retained its vitality for several days. 
Roemer (1915) stored pollen both in cotton-stoppered test tubes and 
in gelatine capsules. He concluded that pollen remained viable longest 
under low temperature (5°-10° C.) and low moisture conditions. 
Tokugawa (1914), using species of Lycoris, Torenia, and Narcissus, 
and Simon (1911), using pumpkin, also found that the pollen lived longest 
in a dry atmosphere. The pumpkin pollen lived for five weeks in a sealed 
vessel containing anhydrous calcium chloride. Adams (1916) found that, 
in a dry condition, apple pollen kept for three months; pear pollen, for 
ten weeks. Strawberry, loganberry, and raspberry pollen were dead 
after two months and black-currant pollen was dead after eleven weeks. 
Horsford (1918) preserved pollen ot Liliwm auratum until the following 
spring by wrapping it in several sheets of paraffin paper and storing it 
in a warm, dry place. It rapidly lost its vitality on exposure to air. 
Anthony and Harlan (1920) worked with barley pollen. They used 
both artificial methods of germination, and germination directly on the 
stigma, as tests of viability. Pollen twenty-four hours old produced a 
greatly decreased percentage of fertilization, while pollen forty-eight hours 
old was incapable of effecting fertilization. Pollen stored under conditions 
which retarded evaporation remained viable for the longest time. 
