MICROSPHAERA ALNI 137 



2. In younger material, study the conidiospores, 

 arising from upright hyphae (conidiophores) . Draw. 



. How are the conidiospores formed, and what is 

 their function? 



3. In older material, scrape off some of the black fruit- 

 ing bodies (perithecia) and study. Draw one of 

 the peculiar appendages. What is the function 

 of the appendages? Crush a perithecium and 

 study the contained sacs (asci) and ascospores. 

 How many asci in each perithecium? How many 

 ascospores in each ascus? Draw to show these 

 points. 



4. What is the function of the ascospore? How are 

 the perithecia formed; the ascospores? Of what 

 economic importance are the mildews? 



