In vitro (Latin for (with)in glass) means within a test tube, or just outside a living organism (a cell). An example is In Vitro Fertilization. The opposite of in vitro is in vivo, within a cell. As many experiments that deal with molecular biology are conducted outside of cells, and the conditions do not necessarily represent the conditions inside the cell, results are often annotated with in vivo or in vitro.
... to the Left (pretty much the Trotskyist idea of "entrism"). The left-wing of the SPA, or the Debs Caucus, including McReynolds, reconstituted the spirit of the SPA and ...