A COMPARISON OF NATURALLY AND ARTIFICIALLY AROUSED IMPULSES UNDER THE INFLUENCE OF NERVE BLOCKS

1. Natural impulses in the phrenic, as well as impulses set up artificially, can be arrested by an electrical (tripolar) block and by freezing mixtures, especially by liquid air. 2. With but one exception, the same strength of block was required for natural impulses as for impulses set up by very weak electrical stimuli. 3. As has been previously shown by other observers, the phrenic nerve is a mixed nerve containing both afferent and efferent fibres. This is definitely proved by stimulating the nerves centrally to a block and thus causing a change in the rate and force of contraction of the opposite slip of the diaphragm.