54 THE THEORY OF NATURAL SELECTION 



observed to take place in the flowers of the Yucca 

 plant of the Southern United States. The act of 

 pollination is performed by a moth Pronuba which 

 possesses special organs particularly adapted for this 

 purpose, in the shape of peculiar maxillary tentacles 

 which are found in no other kind of moth. The female 

 has also a long ovipositor with which she can pierce 

 the tissues of the ovary of the plant, and so lay her 

 eggs within it. With the aid of her peculiar tentacles the 

 female moth collects from several flowers a ball of pollen 

 of considerable size, which she kneads into a firm pellet. 

 She then carries this to a different flower,, and after 

 depositing a few eggs in the ovary she climbs to the 

 top of the style and presses the ball of pollen into the 

 stigma. Thus the ovules of the flower are fertilized^ 

 and whilst some are eaten by the larvae of the moth, 

 others develop into seeds and reproduce the plant. 



The foregoing are perhaps two of the most remarkable 

 cases known of animals having, peculiar habits, and 

 possessing at the same time special organs which render 

 them well fitted for these habits and no others ; but 

 many other cases of scarcely less wonderful adapta- 

 tions have been pointed out. 



Darwin himself indicated the direction in which the 

 study of adaptation was to proceed, and his books on 

 ' Insectivorous Plants ' and on the ' Fertilization of 

 Orchids ' afford us a delightful insight into a number of 

 adaptive contrivances which are to be seen in plants. 

 Another very interesting series of adaptive characters 

 are those which have been gathered together under 

 the heads of Protective Resemblance and Mimicry, and 



