THE ADAPTATION OF THE PLANT TO THE SOIL. 



3 



more than half a century, and the photographs (figs. 1-4) of samples of 

 tm-f taken from the different plots will sho\Y how the vegetation has been 

 revolutionized by the different systems of manuring adopted. At the 

 same time, the diagrams (figs. 5-7) also serve to show how greatly 

 particular species are encouraged by some of the manures, whereas other 

 species are depressed and driven off the plots altogether. 



Here, then, are examples of distinctive floras (and in early June 

 the plots look as though they belonged to different parts of the 



Fig. 2. — Turf from the Plot which has received Phosphates and 

 Potash, but no Nitrogen. 



Clovers, Lathyrus, and other leguminous plants constitute half the herbage. 



country) that have been brought about by artificial means. The 

 factors concerned are all on record and may fairly be expected to dis- 

 close the causes which have led to the redistribution of the herbage. 

 In certain cases the explanation seems obvious enough ; for example, 

 we can see why the manure containing phosphates and potash but 

 no nitrogen should encourage the leguminous plants until they become 

 a good half of the herbage. Such leguminous plants can draw the 

 nitrogen they require from the atmosphere by the aid of the bacteria 

 present in the nodules of their roots. In consequence a mixture of 



B 2 



