Burial at Sea (Bioshock Infinite DLC)

 Thoughts so far

Constants and what? The only thing that kind of bugs me is that there aren't any references to the old plasmids, only the new vigors. Retcon, sure, maybe they're variables.

The Audio Log in the one of the clothes shops at the start of the DLC has Yi Suchong mentioning that somebody got wind of his experimentation into Plasmids and tried to steal his thunder, and thus he developed a way to make Plasmids be digestible in the stomach, hence Vigours.