The pyramidal tract of tupaia, compared to that in other primates

Abstract The pyramidal tract of Prosimii proves to lack coarse fibers and to be much smaller than in Macaca, whereas in Saimiri it resembles the latter very much. Crossing and course within the cord in the Prosimii examined are identical to those in Macaca and Man. In Tupaia the pyramidal tract is very different, as it is very small, crosses to the dorsal funiculus and ends in the lower theoracic levels. The other large tracts descending into the cord seem to enlarge where the pyramidal tract decreases in size and length in Tupaia. The large difference between the pyramidal tract of Tupaia and that of other Prosimii is emphasized.