THE CELL. 



157 



the whole slice is made up of more or less rounded, 

 nearly transparent bodies, rather loosely thrown together, 

 as shown in Fig. 213. Next let us examine, in the same 

 way, a thin slice of the tuber of the Potato. Here, 

 again, it is evident that the object under 

 examination is wholly composed of en- 

 closed spaces, not so much rounded, how- 

 ever, as those'> of the Elder pith, because 

 they are more closely packed together. 

 Fig. 214 is a representation of two of 

 Fig. 213. these spaces. Kow look at the leaf of a 

 Moss, and you see again that we haVe an aggregation of 

 enclosed spaces as before (Fig. 215). So, also, if we 

 examine a hair from the surface of a Petunia or a 

 Geranium, we have some such appearance presented to 

 us as that shown in Figs. 2i6 and 217, the hairs 

 manifestly consisting of several enclosed spaces placed 

 end to end. In short, the microscope reveals to us the 

 fact that every part of a plant^ is made up of surh 

 enclosed spaces, varying greatly in shape and size and 

 general aspect, it is true, but always 

 (except in some of the very lowest 

 plants) clearly exhibiting bound- 

 aries; and since these boundaries 

 are visible, no matter in what direc- 

 tion we make our cutting, it is clear Fig. 214. 

 that the spaces must be shut in on all sides. These 

 enclosed spaces are called cells, and their boundaries are 

 known as the cell-ivalls. 



Pig. 213. — Loosely-packed cells of Elder-pith. 



Fig. 214.— Two cells of Potato tuber containing starch-granules and crys- 

 talloids. (Gray.) 



