THE BATTLE OF LIFE. 113 



and the absence of potash. Ranunculaceae are diminishing, 

 as are also Umbelliferae, Composites, Plantago lanceolata, 

 and Rumex Acetosa. 



As a general rule, it is recognized that the growth of 

 plants is checked if the quantity of potash be reduced beyond 

 a certain limit. Deherain has recently shown that in the 

 case of the buckwheat, starch is not generated from chloro- 

 phyl unless potash be present. If potash be added, then 

 starch begins to be formed. Neither sodium nor lithium 

 can usefully replace potash, though extremely little is 

 known as to the functions of the latter. Salts of potash 

 and magnesia have also a general tendency to augment the 

 weight of leaves, while chloride of sodium favours the 

 development of stem. 



Substitution of mixed mineral manures for ammonia. 



The consequences of the disuse of ammonia, and the 

 employment in its stead of mineral manures, are shown in 

 diminished produce, the grasses having been diminished, 

 the leguminous and the miscellaneous plants increasing 

 in number and proportion. Festuca ovina has been the 

 most prominent grass, while Lathyrus pratensis has mani- 

 fested considerable increase, and Rumex Acetosa has been 

 the most prominent among the miscellaneous plants. 

 < The greatest change after some years was, however, not 

 in the distribution of the species, but rather in the character 

 of their development and their increased tendency to form 

 stem and seed. 



Summary. From the foregoing details it is manifest 

 that the plants found on the several plots vary very greatly 

 in number, in character, and in degree of development, 



