Abstract
The retinal induction set up by a colored patch around its retinal image disappears when a remote region of the retina is illuminated by another colored light complementary to the former. The mechanism of this phenomenon is such that the retinal induction is neutralized by some spreading process originating in the remote region illuminated. Such a process is called “spreading induction.”
The propagation of spreading induction is blocked at an image and at an after-image of a white patch. Taking advantage of this phenomenon, the velocity of spreading induction was measured in 7 cats and in 6 human subjects. The values obtained were on an average 1.83± 0.05mm./sec. in cat's retina and 1.72±0.01mm./sec. in the human retina. The velocity was found uniform throughout propagation. It depended neither on the direction of propagation nor on retinal location.
The velocity was found independent of the kind of spreading induction. The energy of spreading induction suffers from decrement as it is propagated, but its velocity remains uniform. In these aspects the type of energy transmission of spreading induction is different from that of nervous conduction which follows the all-or-nothing law.
