101 
The ability to produce these primordial leaves is not, however, 
confined to the seedling. I have shown, for example, that in 
one of our western pines, Pinus ponderosa, shoots, which nor- 
mally would bear only thin, brown, papery scales, namely the 
shoots which bear the male, or pollen-bearing cones, may be 
made to aa true primordial leaves by the mere pruning 
away of the upper part of the shoot ne in thespring. It is thus 
possible, aie to cause shoot, which normally 
would produce if any, only ee leaves, to produce the 
flattened, primordial kind of leaf. A comparison at this point 
with our larches will show that what may be induced experi- 
mentally in the pine is normally produced in these trees, for the 
new shoots of the larch always produce leaves which are not fasci- 
culated and which produce the morphological equivalents of pine 
fascicles in the form of short spurs. It is interesting in this con- 
nection also to recall that certain fossil forms found in Siberia, 
which are, it is probable, either the progenitors of the pines or at 
least lie close to the family stem, produced normally both kinds of 
leaves. After the fashion of the larch, the plant which has caused 
the writing of this short paper, Pinus pinea, we may regard as 
harking back to an unusual degree during its earlier develop- 
ment, to this geological type, but only in a quantitative sense 
does this plant differ from seedling pines in general. 
In similar fashion a number of species of our native pines, 
after they have been cut down, produce water shoots in the 
manner familiar to us, following the cutting down of many of 
our deciduous trees. These shoots also bear at first only the 
primary leaves. 
This condition, which may be induced in some pines by wound- 
ing, occurs normally in certain species in our southeastern states. 
Here a second growth is frequently induced by the protracted 
season, and the autumnal shoots, as well as the earlier spring 
growth on smaller plants, bear flattened primordial leaves, some 
of which may produce fascicles in their axils, though many do 
not. 
The general subject, suggested by the behavior of the specimen 
before us of the heteromorphy of coniferous leaves, is one of 
