CELLS, VESSELS, AND TISSUES. 



6 7 



in which they may divide ; but generally the nucleus 

 and protoplasm divide into parts, and a new cell wall 

 is formed between them, so that there are two cells 

 instead of one.* Thus the division goes on, and a 

 collection of cells is formed, which is called tissue ; 

 and so the whole plant is developed, or grows up, 

 from " cells." 



The simplest form of tissue is made up of simple 

 cells. It is therefore called cellular tissue, and is of 

 two kinds according to the general shape of the cells 

 of which it is composed. If we were to get some of 

 the pith of the elder,! we should find that it was made 

 up of a lot of cells about as long as they are broad. 

 These are called " short cells," and such a tissue is 

 called "parenchyma "| (Fig. 143). 



But if we carefully 

 separated the parts of 

 a stern, we should find 

 in it long and narrow 

 cells. These overlap 

 one another and so 

 form a stiff tissue, which, 

 though long and narrow, 

 is able to stand upright 

 and carry weight, as in 

 the stem of a butter- 

 cup. This kind of tissue, 



Fig. 144. Cellular tissue 

 (prosenchyma}. 



* cf. Cell in the Appendix. 



f Try this with your magnifying glass ; also pith of dahlia. 



t From the Greek "para" beside, and " encheo" to pour in. 



