Excerpt from Natural Science, 1899, Vol. 14: A Monthly Review of Scientific Progress The conclusions reached are, as indicated above, that on the one hand spinosity represents the limit of morphological variation, and on the other the decline or paracme of Vitality. That is to say, alike in ontogeny and in phylogeny spines increase until maturity, and there is then in old age an extravagant differentiation followed by a decline of spinous growth, and ending in extreme senility with their total absence. In other words, the great development of spinose organisms in a group represents the beginning of the decadence of the group. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.