478 Smith. — Cytological Studies in the Protococcales. II. 
Previous to zoospore formation there is a period of active simultaneous 
nuclear division resulting in 1 6, 32, 64, or 128 nuclei within the cell. 
The zoospores are formed by cleavage. The cleavage is progressive, 
forming first multinucleate protoplasts and later uninucleate ones. 
The pyrenoid disappears previous to or during the first stages of 
cleavage. 
After cleavage is completed the nuclei become dense, and the line 
of demarcation between the protoplasts disappears, reappearing shortly 
before the zoospores are liberated. 
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