The fact that when the leg on the side where the anterior roots have been severed is stimulated the animal moves the other, is sufficient to show that the sensory connections between its surface and the cord are not destroyed by cutting those anterior roots; and we may conclude - taking the other facts just mentioned into account - that the afferent fibres are situated in the posterior roots.
We can confirm this result by cutting the posterior roots on one side of a recently-killed frog, and repeating the stimulation of the feet.
Pinching the limb whose posterior roots are cut, gives rise to no response, because the impulses cannot reach the spinal cord; but stimulation of the sound foot causes obvious movements of both legs. This shows that the section of the posterior roots of one limb cuts off the afferent (sensory) communication on the side operated on, but that the efferent (motor) impulses can pass freely to the muscles, even when the posterior roots are divided, for the limb moves on pinching the other foot. If the proximal ends of the cut posterior roots be stimulated, motions are produced showing that the centres in the spinal cord are influenced by the afferent impulses carried by those posterior roots. If the distal ends of the cut roots be stimulated no movement results.