Manc/ifster Hfei/ioirs, J\>/, Iviii. (19 14), A^^. 0. 7 



frcm the completely manured plots C0.963 and i'465). 

 The artificial culture solution of high concentration 

 yielded heavier plants (0943), approaching those obtained 

 in tile solutions from the completely manured soils, 

 though still below tiie maximum. The soil solutions 

 from the unmanured (1,0) and imperfectly manured plots 

 (2A) yielded plants of a much lower order of magnitude 

 (o'2i6 and 0"486). The addition of the missing nutri- 

 ents to the solutions from the imperfectly manured soils 

 produced growth approaching the maximum (r2i4 and 

 ri54) ; when the nutrients were added to set up the 

 higher concentration the growth produced was equal to 

 that obtained from the artificial culture solution of the 

 same concentration (o"974 and 0"925 against 0'943), 

 though still below the maximum. These results amply 

 confirm the conclusion drawn from the previous set of 

 experiments — that the growth of plants in the soil solu- 

 tions is in the main determined by the amount of plant 

 food the}' contain. One other point was suggested by the 

 results, that the soil solutions, particularly those from the 

 soil of the dunged plot, were better media for growth than 

 the artificial culture solutions of equivalent concentration, 

 possibl}' owing to the presence of soluble nitrogen com- 

 pounds specially valuable to the plant in the earlier stages 

 of growth. On the other hand it is unsafe to lay much 

 stress on such differences in weight as were exhibited in 

 the growth of the plants in the solutions regarded as 

 complete (0943, 1-214, 0-974, i'i54. 0-925, 0-963, 1-349, 

 1-465, 1-286). 



In order to check the conclusions still further a third 

 series of experiments were made. A solution containing 

 per million 4-5 of phosphoric acid and 26 5 of potash was 

 taken as a standard, this being the approximate com- 

 position of the solutions of soils from the completely 



