122 PLANT DISEASE 



velopment of rust. At the same time the 

 straw is so strong and stiff that it never lodges 

 or falls down, although United States Com- 

 missioner Capron tells us that nowhere are 

 heavier or more violent gales experienced." 



Professor Bloxam, in his Organic Chemistry, 

 says 



" that silica is shown by its presence in the 

 shining outer sheath of the stems of the grasses, 

 and creates, particularly in the hard, external 

 coating of the Dutch rush used for polishing." 



It is certain the stem of a plant containing 

 the maximum of silica would be more impervious 

 to the fungus than one wanting in silica, and 

 it would also be stronger and not so likely to 

 be laid. 



Professor Vogel, a German authority, 



" insists that plants growing in soils rich in 

 silica, but poor in humus, generally take up 

 much less silica than plants grown in soils rich 

 in humus though poor in silica. He holds that 



