I'm going to look further into this, but this is what i have found so far: (trying not to throw up)
1 says it is made from decaying cow hydes
another says snouts an knuckles
another pig skins
and another says from any part of the animal that has collegen
and i also found a study that was done (not to scare you) that was questioning if animals from country's w/ mad cow disease could give us that disease.....not only from "jell-o" but from other things including makeup and skin creams, cake mixes and gummy bears, vitamins, gel caps used for drugs and even vaccines.
here's the link if you'd like to see
http://www.cnn.com/HEALTH/9704/24/nfm/
sorry to gross anyone out....just giving the facts