[md2lgyk]

I believe that is what called "checking." Other than cosmetically, it's not a problem and quite common. However . . . .

Is this a new house? Every one I've ever seen used steel columns for this instead of pressure-treated posts. PT lumber inside a house is generally not considered a good idea. Are there footers underneath the posts, or do they just sit on the basement floor? If that's the case, it's wrong.

 

[md2lgyk]

Thank you so much for easing my concern. The 3-story house was built in the late 1890s, and the the 6x6s are mounted on some metal thing which is anchored into the concrete floor.

That "metal thing" is not a footer. Do you know when the concrete floor was poured? Any footers would've been poured first. If you have none, you have a problem.