This substance, commonly known as Barkstone, by trappers and

fur dealers, is obtained from the beaver, and is a remarkable aid in

the capture of that animal. It is an acrid secretion of a powerful

musky odor, found in two glands beneath the root of the tail of

the beaver. These glands are about two inches in length. They are

cut out and the contents are squeezed into a small bottle. When

fresh the substance is of a yellowish-red color, changing to a

light-brown when dried. Both male and female animals yield the

castoreum, but that of the male is generally considered the best.

Castoreum is a commercial drug, and in many beaver countries it

is quite an article of trade. There are other sacs lying directly

behind the castor glands which contain a strong oil of rancid smell.

This should not be confounded with the Castoreum.