CHAPTER II 



PLANT PHYSIOLOGY 

 " In Nature's infinite book of secrecy I can a little read." 



The learning of the gardener and horticulturist 

 embodied from ancient times not a little know- 

 ledge which we now call physiology, but it was 

 long in acquiring scientific value. It is impossible 

 to believe that the old practice of caprification 

 (concerned with the pollination of the fig), or the 

 equally ancient practice of dusting the female 

 date-flowers with pollen, were really understood ; 

 and the same must be said of digging, pruning, 

 manuring, and other operations. The old learning 

 was empirical and not scientifically understood. 

 There are few more striking examples of the slow 

 progress of science than the history of the 

 physiology of nutrition in plants. 



The constituents of plants may be divided into 

 two classes — organic and mineral, and these are 

 composed of a number of elements all of which are 



