864 THE AMERICAN NATURALIST.  [Vou. XXXII. 
gradual opening of the pods prevents the supply from all going 
at one time in one direction or in one day, when a better day 
may arrive. 
We shall find nearly or all flattened seeds or fruits are one- 
sided, unbalanced, and more or less twisted, so in falling to the 
ground they whirl about and are thus kept much longer in 
the air'than they would be if shaped more like a winged arrow. 
Even the wings on the fruit of some of the ashes are twisted, 
though many of them are flat. 
There are a number of rather weedy-looking herbs, common 
to woods or lowland, known as avens (Geum). They are closely 
allied to cinquefoil, and all belong to the rose family. The 
slender styles above the seed-like ovaries of some species of 
avens are described not as jointed, but straight and feathery, 
well adapted, as we might suppose, to be scattered by the wind, 
while others are spoken of as having, when young, styles jointed 
and bent near the middle. In maturing, the lower part of the 
style becomes much longer and stouter. When a whole head 
of pistils has drawn all the nourishment possible, and all that 
is needed from the mother plant, the upper part of each style 
drops off, leaving a sharp, stiff hook at the end. At that time 
each pistil loosens from the head and can be easily removed, 
especially if some animal touches the hooks. To help in hold- 
ing fast, there are a number of slender hairs farther down the 
style which are liable to become more or less entangled in 
hairs, fur, wool, or feathers. Even in the small number of 
plants here noticed, we have seen that scarcely any two of them 
agree in the details of their devices for securing transportation 
of seeds. I know of nothing like the Geum we are now con- 
sidering. When young and green, the tip of each hook is 
securely protected by a knob or bunch with a little arm extend- 
ing above, which effectually prevents the hook from catching 
on to anything, but when the fruit is ripe, the projecting knob 
with its little attachment disappears. 
Nycandra physaloides, or Apple of Peru, a coarse annual 
sometimes cultivated, is spoken of by Gray as bearing dry 
berries. Each suspended berry is covered by a five-parted 
inflated calyx. The edges of the sepals come together and 
