Fissiparous: applied to that form of asexual generation in which the parent divides; each part becoming a new individual.
"Explanation of Terms Used in Entomology" by John. B. Smith
Therefore, in all cases of fissiparous division, the seat or origin of the process is the nucleus.
"Darwin, and After Darwin (Vol. 1 and 3, of 3)" by George John Romanes