58 



BOTAL HORTICULTURAL SOCIETY. 



dioecious, a circumstance which obviates all difficulties about 

 doubtful extirpation of anthers in the female parent, they are 

 peculiarly fitted for the purpose, and as their pollen is so heavy 

 that it falls at once to the ground when ripe, instead of floating 

 in the air, and is, moreover, covered with a raised delicate network, 

 it is peculiarly adapted to adhere to the hairs of insects, without 

 whose help it scarcely ever reaches the female plant, which is 

 often at a great distance from the male. Multitudes of insects, 

 however, greedily search out the blossoms of either sex, and in 

 consequence impregnation seldom fails in wild plants. 



In this appetency for the flowers, it is of the greater importance 

 in the course of experiments to find some effectual way of pre- 

 venting the access of insects. For this purpose cylinders were 

 made of thin tarlatan, 2-3 inches wide, and 6-12 inches long, 

 furnished with a string at either end to tie them closely to the 

 branches, and strengthened in the centre with two or three bands 

 to prevent them collapsing. To show that the insulation was per- 

 fect some flowers were left to themselves ; and not a capsule set. 

 In the case of those flowers which were artificially impregnated, 

 so soon as the stigma dried and the ovary began to swell, the 

 cylinders were removed as no longer necessary, and replaced when 

 the seed was nearly ripe, to prevent its being carried away by the 

 wind. The spikes having the male blossoms, moreover, were sepa- 

 rated as soon as the anthers began to burst, and placed in water 

 to prevent the access of insects. The pollen was applied with a 

 camel' s-hair pencil, and a separate pencil used for each kind of 

 pollen, which was always taken from the same individual and, as 

 nearly as possible, normal plant. 



For the impregnation of early flowering species with those 

 which blow later in the season, the fact was of great importance 

 that the pollen of willows retains its potency for some time. In 

 some cases pollen ten days old was efficient, while the vitality 

 was still further prolonged by steeping it in a solution of honey, 

 made of as much as will lie on the point of a knife, mixed with 

 two ounces of water. Fresh pollen, placed in this mixture, fre- 

 quently began, in the course of ten or twelve minutes, to put 

 forth its tubes. Pollen of Saline silesiaca, eight days old, seemed 

 almost as potent as ever; in twenty-eight days the traces of 

 vitality were very slight, while that of Salix cinerea had become 

 weak in sixteen days, though still capable, after immersion for 

 three hours, of slowly developing its tubes. On the whole it 

 should seem that pollen kept in a dry, cool, shady place,; may, 



