112 * 
22. The thin outer hyaline sack,—the old oogonial wall. Is there 
any trace of the old antheridium? 
23. Fhe uniformly thick hyaline inner wall surrounding the 
oily protoplasm,—the living part of the oospore; why oily? 
24. The dark colored irregularly thickened outer wall enclosing 
the inner wall. This consists of worthless unused protoplasm contracted 
about the inner wall as a protection. 
The thicker inner wall serves as a stored food-reserve for the germinating 
oospores. It dissolves from within as the germinating spore develops 
the long conidiophore with the primary conidium (already studied). 
DRAW to show the structure of a mature oospore. 
Secondary Cycles are initiated repeatedly during the season on leaves, 
stems and fruits by the conidia from primary and other secondary lesions. 
These conidia germinate, as do the primary conidia, by swarmspores. The 
secondary cycles repeat in ali details the phenomena of the primary cycles. 
Only in the leaves, so far as known, are the cycles completed by the forma- 
tion of oospores. 
REPORT 
1. Describe in detail two methods, one an eradicatory, the other 
a protective method for the control of the downy mildew of grapes, and 
state concisely why each should be effective. 
