PART II 

 THE VEGETATIVE FUNCTIONS OF PLANTS 



CHAPTER IV 

 LOSS OF WATER 



28. Plants are Alive. — The most fundamental concep- 

 tion of a plant is that it is alive, just as truly and in the 

 same sense as is any animal. Therefore it takes in water 

 and food, respires, grows, moves, responds when stimu- 

 lated, reproduces, grows old, and dies. We are so ac- 

 customed to associate life with activity that one who, 

 for example, views a large tree, especially in winter, 

 stripped of its leaves, and apparently motionless, except 

 when swayed by the wind, is not always conscious of the 

 fact that the tree really is alive. A study of p'.ants, 

 however, teaches us the fallacy of the idea that life is 

 always associated with evident motion. 



29. Kinds of Vital Activity. — Everything a plant does 

 affects either one of two things — either (i) the main- 

 tenance of the individual, or (2) the perpetuation of 

 the race to which that individual belongs. These two 

 classes of functions are known, respectively, as (i) 

 vegetative and (2) reproductive. This and the next five 

 chapters will deal with the vegetative functions of plants. 



30. Loss of Water Demonstrated.— If a leafy branch, 

 cut from any plant, is laid aside for a time it will, as is 



