Vertebrate Zoölogy

Abstract

THE leading feature of this book is an attempt to interpret the structure of vertebrate animals in terms of the “axial gradient theory.” This theory, enunciated by the author's colleague, Prof. Child, is based upon certain facts of vertebrate development. These show that along the three axes of the body—longitudinal, vertical, and transverse—the rate of differentiation is not uniform, but progresses more rapidly in one direction than in the reverse. Thus the head develops faster and farther than the tail; the dorsal organs (such as the nervous system) than the ventral; and the tissues adjacent to the middle line than the outer tissues. The flow of matter and energy along these axes is apparently faster in certain directions, or the developmental impulses are transmitted more rapidly in these directions, than in others.

Vertebrate Zoölogy.

By Prof. H. H. Newman. Pp. xiii + 432. (New York: The Macmillan Co.; London: Macmillan and Co., Ltd., 1920.) 16s. net.