Abstract
Fifteen rabbits have been transected in the lower thoracic region and have been kept from 3 to 17 days. They ate rolled barley and lettuce and drank water in a normal manner. They defecated and urinated but it was found necessary to evacuate the bladder by pressure upon the abdomen to prevent excessive retention. Trophic disturbances were avoided by keeping the animals and cages clean.
They were observed from day to day for ipsilateral and crossed reflexes in the hind limbs. Ipsiflexion, crossed flexion and occasionally crossed extension were present 24 hours after transection. Crossed extension, however, did not usually appear till about the third day and sometimes later. At first it consisted of extension at the knee and flexion at the ankle and toes. This usually changed to extension at all joints. The Stittz positive reflex became well-developed about the third day. Rhythmic stepping and hopping did not usually appear till after 4 days and they became more pronounced and greater in amplitude from day to day. In the same animal, it was possible to elicit hopping at one time, then after a short interval stepping would be present. Some of these animals were able to support their weight in the standing position but this was more poorly developed than in the cat. In the rabbit, there is considerable resistance to passive flexion in certain positions which is not due to muscle contraction for it can be obtained in the dead animal.
It was possible to anesthetize with ether, then to dissect and isolate the gastrocnemius and anterior tibial muscles. The animal was then placed in a frame and the muscles prepared for recording reflex responses according to the method we have described. 1
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