MEASUREMENT OF THE RESPIRATORY VOLUMES OF LABORATORY ANIMALS

Abstract

A new method for recording the respirograms of laboratory animals has been devised. Animals breathe into a headpiece connected by large tubing to a system of chambers which provide a constant flow of fresh air through the headpiece. As the animal breathes, the pressure within the chambers varies, minutely displacing the leaves of an electrical condenser, and by means of a special electrical apparatus a wave is made to rise and fall on the screen of an oscilloscope. The respirogram is then recorded by a continuous camera. Respiratory vols. measured by this method and by valve methods were found to be (in ml./min): mouse 24.5, cotton rat 39.6, hamster 60.9, white rat 72.9, guinea pig 155.6, rabbit 800.0, monkey 863.5, man 8732. It was found that the respiratory vol./min. varies from mice to men approx. with the 3/4 power of the wt.