PUCCINIA GRAMINIS 131 



2. On the upper surface observe the small dots, the 

 pycnia (pycnidia, or spermatia). What is their 

 color? Their shape? What relation does their 

 position bear to that of the secia? 



3. Study both aecia and pycnia with the aid of a hand 

 lens. Describe carefully the appearance of the 

 infected areas. 



4. Make a drawing, life size, of the barberry leaf, show- 

 ing the features under C, 1-3. 



D. Microscopic Characters: 



1. Study longitudinal sections through an aecium, 

 using low power. 



2. How are the infested tissues of the host affected by 

 the parasite? 



3. Note the aeciospores. Describe their shape. Are 

 they all of the same shape and size? How are they 

 produced? What is the cause of the cluster-cups 

 that appear on the leaf-surface? 



4. Make out all you can of the details of the mycelia, 

 and their relation to the cells of the host-plant, and 

 describe. 



5. Make a drawing of two aecia in different stages of 

 development, one before the epidermis of the leaf 

 has been ruptured. Make the aecium at least 

 30 mm. in longest dimension. 



6. Make a study, similar to that outlined in D, 1-5, 

 of the pycnia, as seen in longitudinal section. Ob- 

 serve the slender threads and the minute spermatia. 



7. What is the function of the aeciospore? Of the 

 pycnia? 



UREDO-STAGE (on Wheat, Triticum vulgare) 



E. Naked-eye Characters: 



i. Study the diseased spots on the leaves of the wheat. 



