Like Stinky already said, give them a few weeks before discarding. A lot of the seeds have thicker hulls (as mentioned) and others can remain dormant for a few weeks even when in ideal germinating conditions. You said you cracked it open and the innards looked intact (at least enough to discern a tap root from the rest), so it's possible it would have germinated.

As also said by Stinky, higher temperatures run the risk of fungus and seed-rot. My friend throws his in a wet paper towel, into a plastic baggy, into a dark canvas bag (for light protection), and then on top of the ballast for a 4ft. fluorescent. He gets anywhere from about 70-100% germination success on recently purchased (so presumably fresher) seeds.
gainesvillegreen Reviewed by gainesvillegreen on . What on earth is wrong with these seeds? Hi, I attempted to germinate some bag seeds that I saved from 2005. I have had them on a moist paper towel in a tobacco tin and left them close to the radiator to give them a decent temperature. Five days have gone by and still NOTHING, not a thing. So I decided to do an 'autopsy' on one of the seeds to see if it had an embryo, and sure enough it did, it also had what appered to be the tap root but they don't appear to want to germinate. Anyway I have ordered some fresh seeds so I'll Rating: 5