CHAPTER 11. 



MATEEIALS. 



Before proceeding to grow our barley seeds in order to 

 obtain young plants for the examination of their tissues, 

 it will be necessary to give a brief sketch of the elements 

 of which plants generally are composed. 



Let Plate 1, fig. 1, represent, on a very large scale, a 

 minute bladder, distinguishable only as such by the aid 

 of a microscope. This, when cut across at a right angle 

 to the direction of its length, or horizontally, would have 

 the appearance represented at fig. 2, seen in perspective. 

 Suppose a number of such bladders to be held together 

 at certain points of their surfaces, and their ends to lie 

 in different planes ; if a knife-blade were passed throug]'' 

 them, as in the previous instance, the section would have 

 the appearance represented at fig. 3. A second cut 

 through such a tissue, in the direction of the transverse 

 line, would divide three of the bladders just above their 

 ends, and w^ould escape the other two. Now we have 

 only to call these suppositious bladders vegetable cells, 

 and their skins the cell-ivcdls (in nature much more 

 transparent than these skins), and we have a tolerable 



