PART I. 



CHAPTER I. 



TnE VEGETABLE CELL IN GENERAL : ITS STUCTUEE, COM- 

 POSITION, AND PKINCIPAL CONTENTS. 



lie. The unit in Vegetable Anatomy, the fundamental compo- 

 nent of which the fabric of plants is constructed, and from which 

 all the diverse histological elements are derived, is the cell. 

 Even the elements which are the least cellular in appearance, 

 and wliich have names of their own (as fibres, ducts, etc.), are 

 onl}' transformed cells, or simple combinations of tliem ; so that 

 the cell is the t3pe as well as the unit of vegetable structure, 

 as indeed it is of animal structure also. The name cell is one 

 which would not be given to it if the nomenclature were to be 

 founded upon our present knowledge. Cells were original!)' 

 taken to be onl}' closed cavities in a vegetable mass.' We now 



1 The earliest recognition of ceUuIar strncture in plants appears in Robert 

 Hooke's MIcrograplila (1665), p. 113. "Our microscope informs us that 

 the substance of cork is altogether fiU'd with air, and that that air is perfectly 

 enclosed in little boxes or cells distinct from one another." 



Nehemiah Grew, of London (The Anatomy of Plants, book i. p. 4), under 

 date of 1671, says of the mass through which the framework of a young 

 plant is distributed, "It is a Body very curiously organiz'd, consisting of an 

 iniinite number of extreme small bladders," etc. 



Malpighi, of Bologna, in a work presented to the Eoyal Society in the same 

 year, uses nearly the same language: "Exterior etenini cuticula utriculis, seu 

 sacculis horizontali ordine locatis, ita ut annulus effornietur, componitur, etc." 

 (Anatomes Plautarura Idea, p. 2). 



As a preliminary study, a beginner .should prepare and examine a few sec- 

 tions like the following : — 



(1) From the tip of the root of a bean (which has germinated on wet sponge 

 or paper) cut a thin section lengthwise, and carefully examine it under a 

 power of 200-400 diameters. If the section is thin enough, the contents of the 

 cells can be made out, and will be seen to consist of a colorless lining (proto- 

 jilasm), in which one part (ttc nucleus) appears denser than the rest. Next, 

 treat the section with a solution of iodine, and notice what parts are colored, — 

 the protoplasm and nucleus are yellow and brown, but the cells on the looser 

 part of the tip contain bluish granules {starch). This starch can best be shown 

 by first dissolving out the prgtoplasm with dilute potash. 



