Excerpt from A Text-Book of General Lichenology: With Descriptions and Figures of the Genera Occurring in the Northeastern United States The systematic arrangement of the families and genera here pro posed is by no means perfect, yet it is hoped that some progress has been made toward establishing a natural system. The fact that most arrangements heretofore proposed had little scientific basis is due to the lack Of knowledge of the morphology and physiology of these plants. Even now our methods of physiological investigation are too imperfect to allow us to Obtain any satisfactory data in regard to the life-history of the individual lichen. Until our methods of investigation are more perfect, all systems of classification must Of necessity be more or less artificial and subject to changes. 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.