Abstract
1. A simple device sensitive enough to demonstrate the tonic neck reflex in healthy human subjects is described. It enables us to measure the magnitude of the reflex flexion or extension of the fore-arm at the elbow-joint.
2. The regularity of the reflex effect exactly follows the formulation of Magnus and de Kleijn.
3. Intensity of the tonic neck reflex is stronger in lower ages; it gradually diminishes as the age advances from juvenile to adult stage.
4. Enhancement of the reflex intensity was observed in cases of oxygen deficiency and lack of sleep.
5. Negative correlation between the intensity of the tonic neck reflex and the ability of quick repetitive movement was shown.
