390 



difficult to give a clear and concise account of the general features of the 

 rusts on account of the inadequate and ambiguous terminology at present 

 in use. It appears to be unquestionably established that the spore struc- 

 tures of the rusts are not to be hoinologized with those of the Ascomycetes, 

 and that taxonomic practice in the rusts should not be influenced by what 

 is correct or expedient in the Ascomycetes or other fungi with strongly 

 marked conidial and sexual forms, but be based upon the unique char- 

 acters of their own development. 



Right conceptions of the rusts, according to the writer's position, are 

 those based upon the full life histories of the species, taking into account all 

 the present known facts, and wrong conceptions are based upon partial 

 life histories, and on ideas derived from other fungi and formerly supposed 

 to apply to the rusts but now known to be inapplicable and misleading. 



Purdue University, 



Lafayette, Indiana. 



