125 



Similar experiments on maize showed a similar acceleration of the 

 date of ripening, as given in the following table, which also shows 

 in the last cohnnn what proportion of the maize was unripe in the 

 sparsely jilanted plats when that which was closely planted was 

 already fully ripe. 



MAIZE (WOLLNY, 1875). 



A striking illustration of the effect of scant water supply is given 

 in the case of four plats of flax, which were sown at the rate of 

 50, 100, 150, and 200 grams of seed per 4 square meters of ground. 

 During the drought of 1875 the plants sown most closely all died 

 early in July, whereas those sown most sparsely withstood the drought 

 very well ; of the plants sown with intermediate densities the number 

 that died was proportional to the density. In general, if all other 

 conditions are the same, plants ripen sooner and have a shorter dura- 

 tion of vegetation in proportion as the soil is drier, or in proportion 

 as there are more plants to the unit area. 



Evidently the plants whose roots extend the farthest in search of 

 water will outlast the species or varieties whose roots are of smaller 

 dimensions. 



RAINFALL AND SUGAR BEETS. 



Briem (1887) has investigated the effect of rainfall on the harvest 

 of sugar beets. His observations were made at the experiment station 

 " Grobers." A long drought during August and September was fol- 

 lowed by a rainy period of many weeks. During the latter the beets 

 increased in weight on an average for each beet from 388 to 450 

 grams; the presence of sugar was shown by the ordinary polariza- 

 tion test, both before and during the rainy period. The following 

 table gives the results of the analyses, each figure being the average 

 of 16 readings on samples taken from 100 beets. These samples show 

 that immediately after the first rainfall, on September 21, the per- 

 centage of sugar per beet diminished somewhat, but that toward the 



