vi THE LIFE OF THE PLANT 



to see the external forms of our common plants. But 

 how different is the case when we are expected to show 

 even the commonest phenomena of plant life, for the 

 most part invisible, and in so many respects quite dif- 

 ferent from the familiar manifestations of animal life ! — 

 think only of respiration without inspiring and expiring, 

 or of feeding on air. At every step we require more or 

 less complicated, or, what is highly desirable but not 

 so easily attainable, the simplest possible apparatus.^ 

 Moreover, all the results obtained must be considered 

 from the general point of view of those two sister (or 

 rather mother) sciences — physics and chemistry. In 

 this respect I have consistently complied with Professor 

 Armstrong's precept^ to which I readily subscribe: 

 ' Whatever we teach in our schools, chemistry must not 

 be neglected ; it is the science of life, life being but a 

 succession of chemical changes : it is therefore the basis 

 of physiology.' 



I fully expect that not a few of my botanical colleagues 

 may consider some passages of chapter vii. out of date ; 

 but I must frankly confess I consider a return in a certain 

 sense to the sound notions of Andrew Knight or 

 A. P. De Candolle, of Dutrochet or Hofmeister may 

 prove to be a desirable corrective to the alarming spread 

 of the ' Reizphysiologie ' with its morbid outgrowth 

 of ' Neovitalism ' and ' Phyto-psychology,' and their 

 natural corollary, anti-Darwinism. Nowadays in our 

 pursuit after the quasi-nervous stimuli we have nearly 

 lost out of sight the object stimulated and the mode of 

 action of the external agents. No less an authority 

 than Sir Joseph Thomson has recently warned us that 



1 I may perhaps be allowed to add that I believe I was the first to 

 introduce lecture experiments into my annual courses on plant physiology, 

 which began in 1870. At least, at a much later date, Professor Julius 

 Sachs, the head of the German school of physiologists, as I was told in 

 1877 by one of his assistants, never introduced any ' Vorlesungsversuche ' 

 into his lectures. 



