CHAPTER VI. 



CELLS AND CELLULAR STRUCTURE. 



Different kinds of cells Cell-cavity, cell-wall, cell-contents Tissues 

 Intercellular spaces, and middle lamella Gas interchange 

 Cell-tissues due to division and partitioning : not to juxta- 

 position Various connotations of the word "cell" The typical 

 cell Embryonic cell Protoplasm, cytoplasm Nucleus 

 Plastids Chlorophyll -corpuscles Vacuole Thickening of cell- 

 wall Vessels. 



It is impossible in a work of this kind to carry our 

 studies far into those regions of minute structure which 

 demand the use of the microscope, but so many pheno- 

 mena depend on the properties of the cell, that the 

 following sketch of the subject of cellular structure may 

 be useful to the reader. 



If we cut a very thin slice through any piece of 

 plant-structure, such as elder-pith, cork, or wood, or 

 through a seed like that of the Bean, or a fruit such as 

 an Apple or a Cucumber, or any ordinary leaf, a root of, 

 say the Carrot, or a tuber such as the Potato in short, 

 through any part of a plant, it is possible to show by 

 means of the microscope that the substance of the section 

 is not homogeneous, but is more or less distinctly 

 chambered. The cavities of the chambers are either 

 empty of all but air or water, or filled with various matters 



52 



