PART L 



CHAPTER I. 



THE VEGETABLE CELL IN GENERAL : ITS STUCTUBE, COM- 

 POSITION, AND PRINCIPAL CONTENTS. 



116. 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 which have names of their own (as fibres, ducts, etc.), are 

 only transformed cells, or simple combinations of them ; so that 

 the cell is the type 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 originally 

 taken to be only closed cavities in a vegetable mass. 1 We now 



1 The earliest recognition of cellular structure in plants appears in Robert 

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

 the substance of cork is altogether fill'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 

 infinite number of extreme small bladders," etc. 



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

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

 sai'culis horizontal! online locatis, ita ut annulus efformetur, componitur, etc." 

 (Anatomes Plantarum 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- 

 plasm), in which one part (the 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 protoplasm with dilute potash. 



