PUCCINIA GRAMINIS 147 



Use the hand lens, if necessary, to make out the 

 features clearly. 



2. Is the shape of the spots (sori, sing., sorus) uniform 

 and characteristic? 



3. State their color. 



F. Microscopic Characters: 



1. Study longitudinal sections, through a uredo-sorus. 

 If the material is not fresh, remove some of the 

 contents of the sorus with a needle, and mount in 

 water. Study under high power. 



2. Describe the color, shape, and relative size of the 

 cells. Are there any surface marks? Do you find 

 any remnants of the pedicel to which the uredinio- 

 spore (" summer spore") was attached? What can 

 you say of the thickness of the cell- wall? 



3. Of how many cells is the urediniospore composed? 



4. Make careful drawings of two or three uredinio- 

 spores, at least 15 mm. in longest measure. 



5. State the function of the urediniospore. 



TELIAL STAGE (on Wheat) 



G. Naked-eye Characters: 



i. Study the telial sori, as directed under E y above. 



Describe the order of their distribution. 

 H. Microscopic Characters: 



1. Study as directed under F, above. 



2. Include in your notes, at this point, a description 

 of the germination of the teliospore (teleutospore) . 

 What is its function? State the function of the 

 basidium (promycelium) , and of the "spring spores/' 

 or basidiospores (sporidia). 



7. General Questions: 



i. What features seem to you to make this parasite 

 easily distributed, and difficult to eradicate? 



