S a 1 m o n , Specialization of Parasitism in the Erysiphaceae. 293 



Fig. 10—12. Contiguous germinating conidia of the Oidium on Bromus inter- 

 ru'ptus, floating on distilled water, after 4 days X 255. 



Fig. 13. Contiguous germinating conidia of an Oidium on an unidentified 

 grass üoating on water showing difference in the manner of germrna- 

 tion X 255. 



Fig 14 — 16. E. Graminis on Hordeum vulc/are] showing the production of 

 ascospores in the asci caused by submersion of the perithecia in water ; 

 14, atter 4 days; 15, after 6 days; 16, free ascospores found in the peri- 

 thecia at the end of 6 days; au X 400 



Fig. 17. An abnormal conidium of the Oidium on Bromus hordeaceus var. 

 glabrescens, germinating on the surface of water, after 4 days X 255. 



Beihefte Bot. Centralbl. Bd. XIV. 1908. 



20 



