1885.] How the Pitcher Plant got its Leaves. 573 
and long petioles, and peduncles like those which are found at 
present in the water-lilies. The other branch diverged to form 
plants living in boggy or swampy grounds, with pitcher-like 
leaves whose insectivorous proclivities were developed later on. 
The development of the members of the water-lily family from 
this hypothetical ancestor can be accounted for thus, The aquatic 
habit must be confirmed, the depth of water increased, the leaves 
grow larger and the change is complete. But to transform a 
peltate or reniform leaf into a pitcher requires much more modi- 
fication. Suppose, however, that water lodging on the upper sur- 
faces of some leaves was retained there ; and that in this water 
insects were caught and drowned. Suppose the constant pres-' 
ence of the water caused the decay of the substance of the leaf 
at its insertion on the petiole and allowed the water to penetrate 
the hollow. This liquid manure might assist the plant in its 
growth. The habit of catching water by means of a peculiarly 
cup-like leaf, would be transmitted from generation to generation. 
Each successive one would have larger and larger petiolar spaces, 
and correspondingly smaller leaves. And this because the liquid 
manure supplied directly to the root would enable the plant to 
do with less and less leaf surface as the nutriment was more and 
more fully elaborated ; until finally the petiole would have grown 
into a hollow pitcher-like affair, and the 
‘ leaf-blade would have dwindled to a rudi- 
ment. 
The primitive pitcher plant was probably 
but little less specialized than the least one 
now known. This one has already been 
described under Heliamphora. The various 
modifications of structure incident to change 
of form now come under consideration. 
The internal hairs of modern water-lilies 
were likely represented in the ancient form | ; 
from which they are descended. In spe- 
cies now living these hairs are stellate, with 
from three to five arms or projections (Fig. Fic. 8.—Internal hairs of 
8), and they thickly line the interior spaces staan A et 
of the petioles of leaves and the peduncles of flowers. Exposure 
to air and adaptation to altered conditions would naturally cause 
a change of form. They doubtless lost first one and then another 
