What organelle reforms around the chromatids at opposite ends of the cell?

Nucleus

Explanation:

Chromatids are the linearly arranged condensed structure of genetic material in the cell. The chromatids are observed after the parent cell are divided into the daughter cells.

During cell division, the cell divides, their chromosomes separate and gets accumulated at the poles of the cell. These chromatids are naked that is floating in the cytosol but the characteristics feature of the eukaryotic cell is the presence of a double membrane organelle which can protect the genetic material called the nucleus.

Thus, nuclear envelope or nucleus gets reformed around the chromatids.

the father in the first generation probably had the recessive colorblind trait in his x chromosome. if he and his wife both had the colorblind trait, even if she had 1 recessive and 1 dominant, then that trait would be passed on to their kids.

(since you didn't attach the family tree this is just an assumption)

his research revealed two genetically different groups of prokaryotes, which justified splitting kingdom monera into two kingdoms. the genetic and cellular differences were so great, that these two kingdoms were eventually placed into different domains in the current three-domain system.