4 THE FERTILITY OF THE SOIL 



that my historical sketch must begin in the seventeenth 

 century, as no Oxford man of science cares to miss 

 an opportunity of recalling the fact that the birthplace of 

 English science was this University. We need not fear, 

 if we look back to the work of the little group of philoso- 

 phers resident here at the close of the Commonwealth, 

 that we shall find they ignored agriculture as a low and 

 mechanic art unworthy of the attention of academies. 

 On the contrary, the Thought they stood for demanded 

 above all things a return to Experience, and they recog- 

 nized that it was in the arts that experience had accumu- 

 lated, the raw material of science had collected, and 

 problems had arisen which would probably have escaped 

 the notice of men confined to the study or the laboratory. 

 It was a point of view which is worth remembering 

 to-day; for, though the Philistine is so much with us 

 that the enthusiast for learning is tempted to despise all 

 useful knowledge, and attach a high value to a line of 

 study only if it be exceedingly remote from practical 

 ends, the fact remains that it is the men who work in 

 a practical way and on a large scale who come across 

 the most stimulating problems. 



BOYLE and his contemporaries, we find, were con- 

 cerned with two aspects of our subject : with how the 

 plant itself grew and how its increased substance came 

 to be, and, secondly, w h the problem of what the soil 

 does towards supplying that substance. The experiment 

 which then held the learned world, the first we find 

 recorded in vegetable physiology, is that of VAN 

 HELMONT, who placed 200 Ib. of dried earth in a tub, 

 and planted therein a willow tree weighing 5 Ib. ; after 

 five years the willow tree weighed 169 Ib. 3 oz., whereas 

 the soil when redried had lost but 2 oz., though the 



