Note 29 — Prop. IV.—That some few remedial agents act locally on the mucous surface, either before absorption, or without being absorbed at all. That they are chiefly as follow:—
Reading edition
Irritant Cathartics, like irritant emetics, may sometimes affect remote parts on the principle of counter-irritation. Some explain in this way the use of purgatives in disorders of the brain, but there are other reasons which serve to account for this still more satisfactorily. (Vide Chap. IV., Art. Purgatives.)