806 THE AMERICAN NATURALIST. [Vor. XXXIV. 
projections of plant tissue, one from the periphery of the leaf, 
and another from the inner surface of the inside scale (Fig. 
5, A). It will be seen by consulting Fig. 6 that the young lar- 
ve are at this time completely surrounded by thin-walled cells, 
and that the plant tissue which is in contact with the body of 
the parasite is composed of epidermis, thus showing that the 
parasite has consumed none of the plant cells or tissues. 
The young epidermal cells of the young normal leaf are long, 
thin-walled, and have little granular contents. The older epider- 
mal cells lose their contents, their outer walls become strongly 
cutinized, and they serve the plant only as a protective covering. 
The epidermal cells of the leaf which are in contact with the 
larvae have an appearance quite different from those epidermal 
cells in the other parts of the leaf. The first difference is 
noticed in the size and shape of the epidermal cells that line 
the cavity in which the larvae lie. 
They are much longer and deeper 
than the normal epidermal cells, 
and they very closely resemble 
the cells lying beneath them, 
which are the large mesophyll 
cells. Furthermore, these epi- 
dermal cells are densely filled 
with granular food matter. Above 
the larval cavity, where the epi- 
dermal cells of the leaf arch over 
to meet those of the scale, they 
are shorter and deeper than those 
leaf epidermal cells touching the 
larvae, but they are much larger 
than the epidermal cells in the 
older parts of the leaf into which 
they insensibly merge (Fig. 6). 
These cells have less contents 
than those in contact with the larvae, but more, again, than 
the normal leaf epidermal cells. 
The epidermal cells on the inner surface of normal scales are 
long, shallow, and thin-walled ; the epidermis on the outer surface 
parenchyma). April 25. X circa 56. 
