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 larve 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 
