118 



maintaining a very constant state of moisture in each, 

 following results: 



with the 



The general result, therefore, was that the largest harvest is given 

 by soil containing 40 per cent of its maximum capacity for water. 

 The general appearance of the plants showed that those having too 

 little water had a less intensive life and were suffering from lack of 

 nourishment rather than from the want of pure water itself. 



Fittbogen (1873) conducted a series of experiments on twenty 

 tubs in groups of four. The relative weights of his harvests of oats 

 were as follows : 



These figures show that for moistures varying between 30 and 80 

 per cent there was very little difference in the' harvest, Avhile for 

 drier soils the harvest was decidedly diminished; but it is notable 

 that for the driest soil (No. 5) the grain ripened earliest of all. 



Haberlandt, in 1875, reports the results of experiments on three 

 tubs sown with summer wheat. The quantity of water allowed to 

 tub No. 1 was just sufficient to keep the wheat alive; the other quanti- 

 ties, with the harvest, are given in the following table: 



Whence it would seem that the limit of useful water had not yet 

 been reached. 



