The relation between the fast vital capacity curves and the maximum breathing capacity.

The maximum breathing capacity (M.B.C.) of an individual is defined as the greatest amount of air he can breathe in one minute. The test in which it is measured was introduced by Hermannsen (1933) as a test of the mechanical efficiency of the respiratory apparatus. Since then it has been widely accepted as fulfilling that purpose and has been quoted (Gray, Barnum, Matheson, and Spies, 1950) as the best single index of the maximum ventilatory capacity of an individual. Many workers have considered that the test is an exhausting one to perform, particularly for subjects with respiratory disfunction, and have, in consequence, attempted to replace it by one which in their view is less severe. The curve recorded by