Could be for a termite treatment, though the holes should have been filled with mortar. (If so, there should be holes around the entire perimeter.)

SOunds like someone started to waterproof the basement and never finished.

The PorchGuy

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Same deal here -- holes with corks in them in my concrete basement. From what I know about my house, I'm guessing that they date from sometime between the mid fifties, when the house was built, and the early sixties.

The home inspector noticed them when we bought the place a few years ago, and thought they were harmless, but recommended filling them if we resold to avoid raising any suspicions with prospective buyers.