AN IMPROVED MICROBATH.

A method is described for the study of the actions of drugs and tissue extracts on small pieces of smooth muscle suspended in a bath with a capacity of 0.027 ml. The small size of the bath is an advantage when the total amount of active substance is small. The contractions are amplified 50- to 500-times and recorded isotonically, or approximately isometrically, with a pen writer. This apparatus has the advantage over earlier models that it is more compact and convenient and that the temperature of the muscle can be controlled. It has been used for the estimation of small quantities of acetylcholine and other substances in tissue extracts.