PHENOMENA OF EEPEODUCTION. 153 



when its transmission is effected by the wind, and especially by insects. ■ Butter- " 

 flies, flies, moths, bees, and often very small Coleoptera may be seen at the bottom 

 of flowers, eagerly seeking the honey, and thus becoming useful auxiliaries in 

 the fertilization of the pistil, either by dispersing the poUen with their wings, or 

 by carrying the pollen of one plant on the hairs of their bodies to another plant 

 of the same species. Here we must notice a very interesting series of coincidences : 

 when the anthers open to shed their pollen, the stigma becomes viscous to retain 

 it ; nectar is distilled by the glands, and nectar-feeding insects make their appear- 

 ance ; lastly, at the same — often very brief — period, the corolla expands, whose 

 colour and scent must affect the powerful sight of insects and their subtle sense of 

 smell. 



Mr. Darwin has recently published, on the fertilization of certain plants, experi- 

 ments which throw a new light on Natural Science, and plainly reveal the marvellous 

 precautions taken by Nature to prevent the degeneration of species. He has en- 

 deavoured to give the rationale of the differences observable in the flowers of Primula. 

 In this genus the same species presents two very remarkable forms : a long-styled, in 

 which the stigma is' globular and wrinkled, and exactly reaches the mouth of the 

 corolla-tube, far overtopping the anthers, which only reach half-way up the tube. 

 In the other form the style is not half the length of the corolla, and the stigma is de- 

 pressed and soft, but the anthers occupy the upper part of the tube, their pollen is 

 larger, and the capsule contains more seeds than that of long-styled individuals. This 

 dimorphism between longistyled and brevistyled primroses is constant ; the two forms 

 are never met with on the same individual, and the individuals of each form are 

 about equal in number. Mr. Darwin covered with netting plants of both the long- 

 styled and short-styled forms, most of which flowered ; but as neither produced seed, 

 he concluded that insects are necessary to their fertilization. But as, in spite of his 

 utmost vigilance, he never saw any insects approach uncovered primroses during the 

 day, he supposes that they are visited by moths, which find abundant nectar in 

 them. He endeavoured to imitate the action of insects, which, while extracting 

 honey from flowers, are the agents of their fertilization, and his experiments led 

 him to very interesting conclusions. If we introduce into the corolla of a short- 

 styled primrose the trunk of a moth, the pollen of the anthers placed at the mouth 

 of the tube adheres to the base of Hie trunk, and it may be concluded that this 

 . pollen will necessarily be deposited on the stigma of the long-styled primrose when 

 the insect visits it. But in this fresh visit, made to the long-styled primrose, the 

 trunk descending to the bottom of the corolla, finds the pollen of the anthers which 

 are situated there ; this pollen adheres to the end of the trunk, and if the insect 

 visits a third 'flower, which is short-styled, the end of its trunk will touch the stigma 

 placed at the base of the tube, and will deposit the pollen on it. Besides this it 

 may be admitted as very probable that in its visit to the long-styled flower, the 

 insect in drawing back its trunk, may leave on the stigma a portion of the pollen 

 from the anthers placed lower down, and the flower would be thus fertilized by 

 itself. It is besides nearly certain that the insect, when plunging its trunk into a 

 short-styled corolla, will have rubbed the anthers inserted at the top of the tube. 



