The writer appreciates the fact that this cannot be other than a very imperfect and inadequate attempt to cover so important and so great a field. He wishes to express his appreciation of the coop cration which has been afforded by his colleagues and begs that all who may recognize any of their handiwork in the following pages will be willing to consider the further dissemination of their ideas a public benefaction, although the author may have failed to give due credit where credit belongs. It has been the intent and purpose, however, to acknowledge all quotations and adaptations in the preparation of these pages. It has been the aim to bring together information which will be useful alike to the student and to the practical grower and to present it in a system atic yet readable form. The author wishes to acknowledge helpful suggestions from Dr. W. W. Tracy, Sr., Mr. W. R. Beattie, Professor William Stuart, Mr. W. A. Orton, Dr. F. H. Chittenden, and others, as well as extracts from their writings; and to make acknowledg ments to the Moninger Greenhouse Construction Company for figures 22 and 2 3 and to the Minnesota Agricultural Experiment Station, the West Virginia Agricultural Experiment Station, and the United States Department of Agriculture for other illustrations.