51�Թ�

When the free ends of the hyphae emerge again into the air they swell up into spherical bodies which may either fall off and behave as conidia, each putting out a germ-tube and infecting the host; or the germ-tube itself swells up into a zoosporangium which develops a number of zoospores.

Each “conidium” contains numerous nuclei and is really a zoosporangium, as after dispersal it breaks up into a number of zoospores.

Motile zoospores which escape from the zoosporangium are present except in Aplanes.

The oospore on germination usually gives origin to a zoosporangium, but may form directly a germ tube which infects the host.

B, a ripe zoösporangium, × 100.