STUDIES IN POLLEN, WITH SPECIAL REFERENCE TO LonGEvity 755 
day for six days. ‘The percentage of fertilizations increased for two days, 
but from this time there was a gradual decrease until, on the sixth day, 
no pollinations brought about fertilization. 
Pollen longevity 
A considerable number of observations have been made by various 
workers on the life duration of pollen. However, as far as can be found, 
few carefully controlled experiments have yet been conducted. 
The earliest reference to pollen longevity is in regard to date pollen. 
Kampfer (1712) states that, if kept in a dark place, it is capable of fertili- 
zation the following year. Swingle (1904) writes that the Arabs make 
a practice of conserving, for use in the following year, a few bunches of 
staminate flowers, which are put in tight paper bags and kept in a dry, 
cool place. Bastin (1910) asserts that there is a tradition that date 
pollen will remain viable for fifteen years or even longer. 
Gleditsch (1751) and Koelreuter (1797) state that the pollen of Chamae- 
rops humilis will live for several weeks. The conditions under which the 
pollen should be stored are not stated, however. 
Gartner (1844) was successful in shippirg the pollen of cycads, palms, 
and orchids. The longevity of many species varied from one to nine 
days. Gartner found no relation between longevity of pollen and length 
of receptivity period of stigma. 
According to Mangin (1886), the duration of life of the pollen of twenty 
different species of plants varied with the species; and among these the 
pollen of Oxalis acetosella lived for only one day, while that of Picea 
excelsa lived for eighty days, and that of Antirrhimum majus for. forty- 
three days. The conditions of storage were not stated. 
Sandsten (1910) found that the vitality of pollen was little affected 
by temperatures ranging from 25° to 55° C. in a dry atmosphere. A 
saturated atmosphere was injurious. Apple pollen was still alive after 
six months storage in a dry place at a temperature of from 8° to 26° C. 
Molisch (1893) stored different species of pollen in watch glasses at 
room temperature and humidity. Longevity of pollen varied from two 
to six weeks, depending on the species. 
Pfundt (1910) has done extensive work on the effect of moisture on 
pollen longevity. Pollen from one hundred and forty species of plants 
was subjected to different percentages of moisture at a temperature 
