PYRAMIDAL TRACT: A COMPARISON OF TWO PROSIMIAN PRIMATES.

The pyramidal tract of the slow loris (Nycticebus coucang) is found in the lateral funiculus of the spinal cord and extends throughout its entire length. Such a course is typical of primates. In the Malayan tree shrew (Tupaia glis) the tract occupies a position in the ventral portion of the dorsal funiculus, and in our studies it could not be traced beyond the thoracic cord. In the spinal cord of the slow loris, pyramidal fibers are distributed to the dorsal, intermediate, and ventral gray columns of both sides, while in the tree shrew they are largely restricted to the dorsal horn and do not cross to the opposite side.