THE BIOLOGY OF CORAL REEFS
235
tion product " which remains in the I' parent " mil. Under certain conditions not yet fully understood, the cell wall thickens (C). These cysts
may then develop into gymnodinioid zoospores (D-E) which in young
cultures may form 80 to 90% of the population. Under other conditions
presumptive zoospores hecome aplanospores (11-19 which, like the
zoospores, becomc coriverted into vcgetative zooxunthellac (F-A ;
E-A). The cyst may also divide (usually into 2, sornctimt:H into 4)
forming autosporcs (C) which rescni M e the purcnt and 011 I i t)cr;Ltiorl