170 THE FERTILISATION OF FLOWERS. [PART III. 
The fleshy thickened base of the coalesced stamens secretes honey 
on the inner surface, which lies surrounding the base of the ovary 
and is only to be reached through two small openings on either 
side of the base of the superior stamen, and the flower is now 
ready to receive insect-visitors (1, 2, Fig. 53). It only remains to 
explain how the downward pressure of the carina is effected. This 
important service is rendered by the ale. They form a platform 
for the insects, and are so combined with the carina that it is bent 
downwards along with them. Each ala has at the base of its limba 
deep depression (3, ¢’), which fits into a corresponding hollow on the 
upper surface of the base of the carina (5, ¢), and close behind this 
spot the upper edges of the alee cohere together. If a bee comes, 
and, whilst clasping the ale with its mid and hindlegs, thrusts its 
head and forelegs under the vexillum to insert its proboscis into 
either of the honey-passages, the ale and with them the carina 
bend downwards, and a quantity of pollen oozes through the tip 
of the carina and becomes attached to the hairy ventral surface of 
the bee. If the bee forces its way further into the flower and thus 
presses the alee and carina down still more, the stigma protrudes 
from the apex of the carina and rubs against the ventral surface 
of the insect. 
The insect’s belly is covered with innumerable pollen-grains 
from the same and from previously visited flowers, and cross- 
fertilisation takes place without fail. And it is scarcely possible 
to doubt, though it is hard to prove by direct observation, 
that the pollen brought from other flowers is prepotent in 
its action. 
Delpino considers that the stigma does not become capable of 
fertilisation until its papille have been slightly rubbed, by which 
the stigmatic surface is made sticky. If this view is correct, cross- 
fertilisation must take place regularly, in the course of repeated 
visits, since the stigma must be cleared of its own pollen before its 
papillze become exposed to friction. In either case it is very much 
to be desired for the sake of a clear understanding of the mechanism 
of this flower, that experiments should be instituted to show 
whether Lotus does or does not produce seed when protected from 
insects, 
The process of squeezing out a little ribbon of pollen by de- 
pressing the carina may be repeated eight to twelve times, if the 
carina is pressed down only a little way each time. But bees when 
collecting pollen press the ale and carina down as far as possible to 
get all the pollen that they can, so that the supply is exhausted 
