Excerpt from Functional Periodicity: An Experimental Study of the Mental and Motor Abilities of Women During Menstruation<br><br>This is a matter of physiology, not a matter of sentiment; it is not a mere question of larger or smaller muscles, but of the energy and power of endurance, of the nerve force which drives the intellectual and muscular machinery; not a question of two bodies and minds that are in equal physical condition, but of one body and mind capable of sustained and regular hard labor, and of another body and mind which for one quarter of each month, during the best years of life, is more or less sick and unfit for hard work.<br><br>About the Publisher<br><br>Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com<br><br>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.