CHAPTER VII 



GROWTH 



IN the folklore of some northern people the gods and 

 diviners are endowed with a faculty for not only seeing 

 but even hearing the grass grow. In the present 

 chapter we shall investigate the question whether the 

 eye and ear of a simple mortal can ever develop such 

 acuteness as to see and hear the growth of a plant. Let 

 us begin by settling in what sense we are going to use this 

 term. By growth, in the narrow sense of the word, we shall 

 understand the increase in bulk of the plant, which takes 

 place as a result of the transformation of the assimilated 

 food-substances into the solid skeleton of its structure, 

 consisting mainly of cell-walls. Thus, although growth 

 necessarily presupposes nutrition, these two processes 

 are not bound to take place simultaneously. Growth 

 can also take place under conditions which make nutrition 

 for the time impossible, as in the absence of light. These 

 two processes may in fact be carried on in different 

 places and at different times. Growth is usually most 

 active in the youngest parts of the plant, which develop 

 at the expense of the activity of organs already developed 

 and serving mainly for the purposes of nutrition. These 

 two main functions of vegetable life, nutrition and 

 growth, are sharply separated in time, particularly in 

 those cases enumerated in our last lecture, where growth 

 takes place at the expense of abundant stores of food, 

 often the accumulation of many years. We have 

 already seen that during germination the increase in 

 bulk of the seedling does not depend on a correspond- 

 ing addition of matter, but is accompanied by a 



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