This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol1", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
Under this name the present U. S. Pharmacopoeia unites the roots of the Rubus villosus or common blackberry, and the Rubus Canadensis (B. trivialis, Pursh) or dewberry; and, as there is no known difference in effects between them, they have been very properly consolidated, instead of being designated, as in the old Pharmacopoeia, by distinct officinal titles. These two species of Rubus are indigenous briers, growing in different parts of the United States.
The roots are cylindrical or branching, with a brown or ash-coloured bark, and a central woody portion, the former of which is of a bitter and strongly astringent taste, the latter is tasteless, and both are without smell. The woody part is inert; and either the smaller roots, or the bark only of the larger, should be employed. Water and alcohol extract all their virtues.
There is no observable difference in the effects of these roots. Both are gentle tonics, and energetic astringents.
Blackberry and dewberry root may be employed for the same purposes generally as the bitter vegetable astringents; but are seldom given except for bowel complaints, in which they are highly esteemed popular remedies. I have used them in diarrhoea with advantage. They are applicable only to chronic cases of this disease, or to such as are connected with intestinal debility; and should not be employed when there is general fever, or any acute inflammation of the mucous membrane of the bowels. They are a favourite domestic remedy in the diarrhoea which follows cholera infantum.
They are usually given in the form of decoction, made by boiling au ounce of the bruised roots in a pint and a half of water to a pint, and administered in the dose of a wineglassful for an adult, a dessert-spoonful for a child two years old, three or four times a day, or more frequently. It may be well to add to the decoction, at the end of the boiling, half an ounce of bruised orange peel, or two drachms of bruised cinnamon, in order to qualify the flavour, and render the preparation more acceptable to the stomach.