82 THE HARMONIES OF NATURE. 



and close their petals in the evening or in rainy weather. The 

 final cause of this is to keep the moisture .from the pollen, lest 

 it should be thereby coagulated, and of course prevented from 

 falling or being blown upon the stigma. Thus, in the organisa- 

 tion of the hermaphrodite flowers, every circumstance which 

 could possibly favour their fecundation has been most admirably 

 attended to ; and though those plants where the stamina and the 

 pistils appear in separate flowers, or even on separate trees, 

 might at the first view seem less well provided for, yet here 

 also the pollen is made to reach the stigma as surely as if both 

 had been produced within the same corolla. 



To effect this object, Nature has two most efficacious agents at 

 her disposal : the wind, and the insects, who by their friendly 

 intervention seem desirous of making amends to Flora for the 

 ravages they are perpetually committing on her domains. The 

 bees are particularly useful in this respect, for, while sipping the 

 sweet juice of the nectaries at the bottom of the flowers, they 

 brush off the pollen from the anthers of one flower with their 

 hairy bodies, and unconsciously convey it to the stigma of 

 another. In the extensive families of the Asclepiadeae and of 

 the Orchids, insect intervention is not merely of assistance but 

 absolutely necessary for their fecundation: as here the ripe 

 pollen, instead of being a loose powder, forms a wax-like adhe- 

 sive mass, which, sticks fast to the honey-gathering insect, and 

 could not otherwise be brought into contact with the stigma. 

 In these flowers the nectaries are disposed in such a manner 

 that, to be able to reach them, the insect must necessarily graze 

 the stigma, and thus bring the fructifying pollen to the place 

 where it is needed, an arrangement which plainly points to the 

 direction of a higher hand. 



As the moistening of flowers generally prevents their fructi- 

 fication, (for the pollen of but very few water-plants, such as the 

 Horn- wort (Ceratophyllum demersam), and the Grass- wrack 

 (Zostera marina), is not damaged by wet), most of the plants 

 that grow below water emerge when their flowers begin to blow, 

 and swim upon the surface till they receive their impregnation, 

 and then sink down. 



Thus in autumn, at the time of flowering, air is developed in 

 the bladders, which here and there distend the linear leaves of 

 the Utricularia vulgaris or Hooded Milfoil, a plant of frequent 



