INTRODUCTION

TO

BOTANY.

BOOK I.

ORGANOGRAPHY ; OR, OF THE STRUCTURE OF PLANTS.

CHAPTER I.

OF THE ELEMENTARY ORGANS.

If plants are considered with reference to their internalorganisation, they appear at first sight to consist of a vastmultitude of exceedingly minute cavities, separated by amembranous substance; more exactly examined, it is foundthat these cavities have a variety of different figures, andthat each is closed up from those that surround it; and if theenquiry is carried still farther, it will be discovered that thepartitions between the cavities are all double, and that bymaceration in water, or by other processes, the cavities withtheir enclosing membrane may be separated from each otherinto distinct bodies. These bodies constitute what is calledVegetable Tissue, or Elementary Organs : they are the Simi-lar 1/ parts of Grew; the Tissu organique of Mirbel; and theParties elementaires, or Parties similaires, of De Candolle .

The chemical basis of the elementary organs has beenfound to be oxygen, hydrogen, and carbon, with occasionallya little nitrogen or azote, combined in various proportions :their organic basis is membrane and fibre. The latter onlyare here to be considered.

JB