PLATE 4. 



Erysipheae. 



Podosphaera tridactyla, (Wallr.). 



Pig. 1. Natural size on leaf of Morello cherry. 



" 2. An enlarged perithecium. 



' 3. Two asci. 



" 4. Four sporidia. 



" 5. A chain of conidia. 



" 6. Two conidia germinating. 



