PLATE XXVIII 



The outlines in this illustration were made on a level table by the aid of the 

 camera lucida, using the Leitz achromatic objective No. 6 (4 mm.) and Huyghenian 

 eyepiece Leitz No. IV (Xio). "The detail was studied tmder a magnification of 1,000. 



Fig. I. — Oats inoculated with Puccinia graminis from Dactylis glotnerata after three 

 generations on oats. Early infection stage, showing haustoria in the two epidermal 

 cells to the right of the stoma and one in mesophyll cell. Host cells normal; infec- 

 tion normal and successful. 



Fig. 2. — Same as figtu"e i, seven days after inoculation. Cell from edge of pustule 

 area siurounded by hyphae, but still normal. 



Fig. 3. — Oats inoculated with P. graminis hordei, four days after inoculation. Piece 

 of mycelium growing over cell ; chloroplasts being destroyed ; cell at right just being 

 affected; haustorium in epidermal cell. 



Fig. 4. — Same as figiu-e 3. Infection thread growing over cell and destroying chloro- 

 plasts ; normal cells on left. 



Fig. 5. — Oats inoculated with P. graminis iritici fbur days after inoculation. Hypha 

 growing over two cells, both of which have been killed ; outlines of chloroplasts still 

 showing faintly in second cell; cell to right of hypha becoming affected. 



Fig. 6. — Oats inoculated with P. graminis triiici, 48 hours after inoculation. The 

 cell on the left killed; outlines of chloroplasts still showing very faintly; cell on the 

 right just becoming affected; tip of hypha dying. 



(200) 



