Page:Collected Physical Papers.djvu/286

266 But is it true that the inorganic are irresponsive, that forces evoke in them no answering thrill? Are their particles for ever locked in the rigid grasp of immobility? As regards response, is the chasm between the living and inorganic really impassable?

Let us take a piece of thin wire from which all strains have been removed and hold it clamped in the middle at C (fig. 64).

A and B will be found iso-electric and no current will pass through the galvanometer. If we now stimulate the end A by a tap, or better still by rapid torsional vibration, a "current of action" will be found to flow in the wire in one direction. Stimulation of B on the other hand, gives rise to a current in the opposite direction. The object of the block C is to prevent the molecular disturbance produced by stimulus at one end of the wire from reaching the other.

Quantitative stimulation is applied by producing a sudden torsional vibration, say of 90°, to the end A, with the result of an up-response of the galvanometer; on application of similar stimulus to the end B, there