Final answer:
In multinucleate species like Valonia, nuclei divide through the process of multiple fission, where a multinucleated cell divides to form more than one daughter cell.
Step-by-step explanation:
The question asks about the method by which nuclei divide in multinucleate species, specifically in the context of Valonia, a type of green algae. In multiple fission, a multinucleated cell can divide to form more than one daughter cell. This process is observed in certain protists and is different from binary fission, which is seen in prokaryotic microorganisms and some invertebrate, multi-celled organisms, where the parent cell splits into two identical daughter cells. In the case of multinucleate species such as Valonia, multiple fission is the method by which nuclei divide to form multiple daughter cells from a single multinucleated cell.