568 How the Pitcher Plant got its Leaves. [June, 
plants, for by so doing it is often possible to find the line along 
which they have descended. It seldom happens that all traces of 
this line have been destroyed. Here anc there a faint or obscure 
mark gives a clue; one thing leads to another, until at last it be- 
comes easy to trace the line of development to the original start- 
ing point. To do this it will first be necessary to give some 
account of the pitcher plants now living in the new world. 
d A 
a 
Fig. 1, 
_ The simplest form of leaf in the family is found in Heliam- 
o phora, a native of Venezuela in South America. It is a hollow 
tube with a narrow opening extending nearly one-fourth the way 
to the bottom, and with a small rudimentary hood at the top 
(Fig. 1). Nearly the whole of the interior of the leaf is lined 
with hairs, those at the bottom long and slender, and those at the 
óp short and thick (Fig. 2). They do not seem to be either 
