substance vs. procedure

The question is whether such a statute concerns merely the manner and the means by which a right to recover, as recognized by the State, is enforced, or whether such statutory limitation is a matter of substance in the aspect that alone is relevant to our problem, namely, does it significantly affect the result of a litigation for a federal court to disregard a law of a State that would be controlling in an action upon the same claim by the same parties in a State court?