Excerpt from Behavior, Under Cultural Conditions, of Species of Cacti Known as Opuntia All this relates, however, to the development of characters economi cally undesirable. It is well known that lack of spines is also a char acter which can be maintained by vegetative propagation, but being usually of slight variation is not as striking as the case mentioned of variation in an opposite direction. This phenomenon is an import ant one for it furnishes a possible suggestion regarding the origin of the spineless varieties. 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.