106 
THE AMERICAN BOTANIST. 
product as the silk of these Asclepiads. The hairs are, 
however, too smooth to felt. If one looks at a cotton- 
fibre under a microscope he will find it to be a flattened 
ribbon-like band, more or less twisted on its own axis. 
This quality permits each hair to stick to its neighbor and 
greatly aids in weaving and such like processes. The milk- 
weed hair, on the contrary, is a simple cylindrical, smooth 
thread. If a method is ever found for using these fibres, 
it seems as if an3^ amount of plants could be grown. But 
value would probably soon produce unexpected enemies. 
Let a plant become of service to man, and at once it is 
attacked by ten thousand enemies, incentives to make us 
work and perhaps swear. 
Some milkweeds are expert fly-catchers, or rather 
butterfly-catchers. We have often seen insect visitors 
caught by the proboscis and hanging helpless as examples 
to their kind. Cruelty is not confined, it seems, to cats or 
small boys ; even plants are not above it. 
Brown University, Providence, R. I. 
BOTANY FOR BEGINNERS— XXI. 
ORDER IV. — PRINCIPES. 
The order Principes has scarcely more than afoot-hold 
in North America, but so large and characteristic a group 
is it in other parts of the world that we can scarcely omit 
some notice of it m passing. The single family Palmaceae, 
the palms, of which there are more than a thousand 
species make up this order. They are found most abund- 
antly in the warmer parts of the world and the individual 
species are often very local in their distribution. 
The Palmaceae is the characteristic tree group of the 
Monocotyledons. While a few species are nearly stemless, 
the great majority assume the proportions of trees and no 
really herbaceous species exist. There is also a vine -like 
group, the rattan-palms, which scramble over other vege- 
tation by means of hooks on the stems and are said to 
sometimes reach a length of three hundred feet. The 
aspect of the arborescent species is so well known that the 
