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574 How the Pitcher Plant got its Leaves. [June, 
projection, till they were reduced to a single one. This one would 
be, at first, of the same size and shape the whole length of the 
pitcher. Then, in time, as it was found that those at the bottom 
would not need to be so strong, they would become longer and 
more slender, while the uppermost ones would be stiff and harsh 
to more effectually prevent the crawling up of insects. As the 
specialization proceeded, a less number of hairs would be required 
and a smooth space near the center of the wall of the leaf would 
be found a still more effective guard against the escape of the 
prey. 
Fic, 9.—Heliamphora, 
As soon as the capture of insects became a necessary part of 
the existence of the plant, or even an advantage to it, honey 
would be developed to serve as an attraction. This, from at first 
a merely sweet secretion, would acquire, if it served a useful end, 
_a character calculated to retain the insect. If, however, the honey 
__ had too bad an effect, the end in view would be defeated, for it 
= would in time be rendered unattractive. For insects would in 
_ their turn, become modified to resist the temptation. So then 
the next step in the onward march would be to keep the honey 
of the lure pure, but to modify the character of the secretion at 
