[Letters to Editor]

Abstract

TWENTY-FIVE years ago it was my privilege to teach Prof. Wood Jones; he now repays me with interest and with some degree of vigour. The matter wherein we differ has a very direct interest, not only for those who are seeking to unravel the history and relationships of man by means of anatomical evidence, but also for every zoologist who relies on structural details for arranging animals in a natural or evolutionary series. In man and in the four anthropoid apes—the gorilla, chimpanzee, orang, and gibbon—the tail has undergone a peculiar transformation—a sacralisation it may be named—for its vertebræ have become a mere submerged appendix of the sacrum. The depressor muscles of the tail have become spread out to form a muscular hammock on which the pelvic viscera are supported. With this sacralisation of the tail there are numerous correlated changes in the vertebræ and muscles of the spine, in the musculature of the body-wall and thorax, and in the shape and arrangement of the viscera of the body-cavities.