It’s commonly thought that the seeds are the spiciest part of a chili, which is the impression Matticus_Rex seems to be under. In fact, the heat comes from the white pith (which they mentioned) and ridges around the seeds.

The seeds are definitely coated in a sticky juice that is spicy (I've seperated them out and eaten them individually. It's the bitterness that really sucks, though.

There's some heat, but the reason I deseed is mostly flavor. Seeds make up a non-negligible portion of the mass, and have no pepper flavor and a slight bitterness. You get better flavor without them.

Seeds make up a non-negligible portion of the mass, and have no pepper flavor and a slight bitterness. You get better flavor without them.