Final answer:
Histone proteins are crucial for maintaining the highly compact structure of metaphase chromosomes, as evidenced by the effects of salt extraction on chromatin structure.
Step-by-step explanation:
The evidence described indicates that histone proteins are essential to maintaining the highly compact structure of metaphase chromosomes. The process of salt extraction can remove most proteins from the chromatin, and depending on the salt concentration, different structural features of the chromatin are revealed. Initially, DNA-wrapped nucleosomes appear as 'beads on a string', and as salt concentration increases, the chromatin transforms into a more compact coil of nucleosomes, or a 30 nm solenoid fiber. During the metaphase stage of mitosis or meiosis, chromosomes become maximally condensed, revealing associations with scaffold proteins. It's these condensed structures that are necessary for ensuring chromosomes withstand the forces exerted during cell division and maintain hereditary information intact.