1902.] 



Starvation on the Parasitism of Puccinia. 



143 



psammophilous plants as the Bromes of the minute quantities of these 

 elements needed for their growth ; the root-hairs appear to be able to 



obtain traces' of these substances from the grains of sand, and it would 

 be necessary to repeat the experiments with some other medium — 

 perhaps precipitated silica or pure quartz— to obtain through starva- 



