CHAPTER II. — SPECIAL PHYSIOLOGY OF THE NUTRITIVE FUNCTIONS. 733 



culation, or rotation : some are capable of locomotiou during the 

 whole or a portion of their life, a peculiarity which is shared by 

 many reproductive cells, such as zoospores and spermatozoids : in 

 some cases, the floral or the foliage- leaves of the plant can perform 

 movements, as the foliage-leaves of the Sensitive Plant, of the 

 Telegraph-plant, of Dionce.a muscipula (Venus Fly-trap), the 

 stamens of Berberis and of the Cynarese, or portions of leaves as 

 the tentacles of Drosera (Sun-dew, see p. 711). These movements 

 are considered in detail in the next chapter. 



The connexion between these various forms of dissipation of 

 energy and the catabolic processes, is clearly demonstrated by the 

 fact that any change which prejudicially affects the activity of 

 catabolism, similarly affects the dissipation of energy. For 

 instance, in the absence of free oxygen, a condition which 

 diminishes catabolic activity in most cases, germinating seeds or 

 opening flowers cease to evolve heat ; the luminous Fungi cease to 

 emit light ; growth, and the other more conspicuous movements 

 are arrested : similar effects are produced by exposure to a low 

 temperature. 



The main facts of the metabolism of the plant may be clearly 

 summed up in a general table of the income and expenditure, such 

 as the following. It may be explained that in this table account 

 is taken of only that portion of the water absorbed from without 

 which actually enters into the metabolism ; the remainder, which 

 simply traverses the plant to be exhaled as vapour in transpiration, 

 is not considered. Under the head of " incidental losses " are 

 included the loss of organic substance connected with throwing 

 oft' reproductive cells, such as spores and spermatozoids, or other 

 reproductive organs such as seeds, bulbils, etc. ; and the loss 

 accompanying the shedding of leaves, etc., in the case of plants 

 which live through more than one period of growth. 



