The ineffectiveness of excitation of the primary endings of the muscle spindle by vibration as a respiratory stimulant in the decerebrate cat.

1. Small-amplitude high-frequency longitudinal vibration (for example, 100 mu peak to peak amplitude at 250 c/s) was applied to the triceps surae muscle of the decerebrate cat without producing any appreciable change in its respiration.2. Manual squeezing of the same muscle produced a large increase in ventilation.3. As vibration is known to be a powerful stimulus for the primary endings of the muscle spindle it is concluded that these receptors are unlikely to have any significant role to play in the reflex regulation of breathing.