Heteroecism. rp 



Whatever view we take as to the cause of heteroecism, it is a well- 

 established fact that the promycelial spores, no matter how freely applied 

 produce no effect on the grasses which bear them, and the most probable 

 theory as to its origin assumes that the uredo and teleuto spore generation 

 were at first associated with the aecidia, but ultimately passed over to 

 other hosts. 



