34 



THE WHEAT PLANT 



dispute. These have shown that when kept in an ordinary dry room 

 grains lose their vitality altogether or have their germinating capacity 

 greatly reduced in ten years or less. 



The rate of loss of vitality is shown in the following records by Burger- 

 stein, Carruthers, and Gross : 



PERCENTAGE GERMINATION 



The grains used by Gross had been stored in open glass beakers or 

 small bags in a dry unheated room. 



In 1907 I tested samples of grain grown on the farmyard manure plot 

 at Rothamsted. These had been artificially dried after harvest before 

 being stored in glass bottles. 



The following results were obtained : 



PERCENTAGE GERMINATION 

 Year of Harvest 



Some of the grains of the harvest of 1882 had retained their vitality 

 for twenty-five years. 



