2 DISEASE IN PLANTS. 



atmosphere are merely reservoirs of more or less 

 inert materials, from which the living plant draws 

 its supplies, and works them up, by means of 

 energy focussed from the sun, into new plant 

 substance. 



In other words, the more far-seeing pioneers of 

 scientific agriculture and forestry, etc., are recog- 

 nising that agricultural chemistry is not the be-all 

 and end-all of agricultural science ; but that, in 

 place of the study of the chemical analyses of dead 

 soil, water, air, and plant-remains, which has so 

 long held sway, largely owing, I think, to the 

 influence of Liebig, the student should have his 

 attention more concentrated on the living plant 

 itself and on the physiological actions which make 

 up its life. He must regard the living plant as a 

 sort of working machine infinitely more complex 

 than any machine made by man, but a machine 

 nevertheless the purpose of which is to store 

 up energy from the sun, and so to add to our 

 wealth on this planet, at the expense of the extra- 

 terrestrial universe. 



It is not, be it noted, that the new study 

 proposes to ignore or abandon the old studies : 

 modern physiology owes too much to the physics 

 and -chemistry on which it is partly based, and to 

 the labours of De Saussure, Ingenhousz, Priestley, 

 and others, for that. But it is that the new 

 study recognises that the central point, to which 

 all views must be focussed, is not the one that 

 it was formerly supposed to be. The student 

 is still taught that the chemistry of soils yields 



