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it would speedily become extinct, but they blossom upon 

 different days, and insects convey the pollen of one to 

 the pistil of another. In some plants the relative size of 

 the organs varies in different individuals so much that 

 they almost seem to belong to different species, and this 

 facilitates the work of the insects. An example of an 

 orchid was given, which has a nectary like a tube five or 

 six inches long, with a drop of nectar at the bottom ; at 

 the top, upon a broad petal, are two small button-like 

 projections, which are the pistils, but the stamens are 

 nowhere visible. The pollen is found in little pockets on 

 the opposite side of the petal, connected with the button 

 by a thread running through. This flower could never 

 be fertilized without the action of insects. The nectary 

 is long and narrow and it is only a certain large and bril- 

 liant species of moth, which uncoils its long tongue and 

 in reaching the nectar strikes with its head the little but- 

 tons at the top of the tube, and as they are covered with 

 a sticky substance, bears them away upon its head, with 

 the thread and packet of pollen attached. As these 

 threads dry they bend forward, and are just in position to 

 touch the stigmatic surface upon the next flower he visits. 

 The help of insects is necessary even where the organs are 

 near each other in the same flower, for Darwin has found 

 by investigation that in many flowers self-fertilization is 

 impossible ; the pollen to be efficient must be carried to 

 the pistil of another flower. All flowers having a bright 

 colored corolla, or fragrance, arc fertilized by insects. 

 Others, and those like the pine, having staminate and 

 pistillate flowers on different trees, arc fertilized by the 

 action of the wind. The insects visit only the most 

 brightly colored and perfect flowers of a species, hence 

 these only bear seed and so the principle of natural 

 selection is constantly operating. 



