When the spinal cord of a dog is cut through, the hind legs, bladder, rectum, and erectile power seems to be quite paralysed, and on tickling the skin of the paralyzed posterior extremity of the dog's body, no reaction follows. This led to the conclusion that the centres for the motions of the bladder, rectum, &c., were situated in the brain. In reality these centres had their seat in the dorsal portion of the spinal cord. Owing to the section of that organ the functions of the parts below were suspended; but after some weeks the inhibited functions again returned. One must, therefore, be very careful in distinguishing the phenomena of inhibition from the residual effects of a vivisection. If one, he observes, pinches the left hind foot of a dog which has just suffered the loss of a portion of the right hemisphere, the animal shows no sign of pain; but neither does he show any trace of other reflex action. If one makes the same experiment with an animal whose spinal cord has been cut through several months before, he draws back the pinched paw very promptly. The centre for this reflex action lies in the dorsal part of the cord. But why does this reflex fail with the dog which has the spinal cord uninjured, but a fresh wound in the brain ? Clearly because the reflex centre on the right side of the cord has suffered inhibition from the fresh wound given to the left hemisphere of the brain.
Email your librarian or administrator to recommend adding this journal to your organisation's collection.