i8 DISEASE IN PLANTS. 



instance the production of osmotic pressures in 

 the cell. 



And, thirdly, part of the synthesised substance 

 is worked up into higher bodies, by processes 

 which obviously entail the further doing of work 

 on the constituents. 



The further pursuit of this theme would evi- 

 dently carry us beyond the more immediate 

 subject of this book ; but I want to make clear 

 that recent researches render it more and more 

 certain that the living plant is a complex piece 

 of co-ordinated machinery which brings together 

 matter and energy from the external universe, and 

 then gets work out of these. 



This proposition is the more important because 

 the whole question of the enrichment of our planet 

 with new food, new building materials, and new 

 fuel, to compensate the daily losses, depends on it, 

 and is of course to be referred fundamentally to 

 the acquirement of new supplies of energy from 

 the sun. Enormous activity has been displayed 

 by physiplogists, since i860, in attempting to 

 solve the question, which of the many different 

 rays known to proceed from the sun are absorbed 

 by the chlorophyll-corpuscle, and directed to the 

 performance of the work above referred to. 



The names of Draper, Sachs and Pfeffer stand 

 forth prominently as pioneers in this ; while those 

 of Lommel, Engelmann, Timiriazeff and Langley 

 have been among the most active in making 

 important contributions to the subject, and in 

 attempting to answer the further questions con- 



