200 STRUCTURE AND VITAL PROCESSES OF PLANTS 



2. -THE ORGANIC STRUCTURE 



1. Phiiits which consist of single cells, like the Bacteria, can 

 bo compared to single men who live for themselves and have to 

 do everything alone, such as gathering of food, building of houses 

 to live in, defending themselves against enemies and so on. 

 So single cells have to do all the functions essential for life: 

 they have to absorb their food and digest it, to excrete waste 

 substances, to guard against adverse circumstances, and to re- 

 produce their kind. 



2. Plants consisting of various cells, however, are like a state, 

 ill wliich the different labours conducing to the welfare of the 

 community are divided. As in the state certain individuals (far- 

 mers) are occupied in obtaining food for all, others (craftsmen) 

 in supplying the public with houses and clothes, others (merchants) 

 in the distribution and circulation of food and articles, and 

 others (soldiers) in the maintenance of order and in the defence 

 of the common-weal, so the various cells of a plant are as- 

 signed different functions and form a well-organised state. 



3. They are also specially fitted for their several special 

 purposes, and groups of them thus form organs for the vital 

 operations of the plant. 



These organs are not equally developed in all plants. Some 

 have a higher, and some a lower organisation. We shall now 

 study the various organs of the plant, as we find them in their 

 leaves, roots, stems, flowers, and fruits. 



