approx 2mlI'm trying to imagine you collecting a vial of spit. I mean, how big of a vial do they need? Does it have to contain cheek cells? Do you have to practically fill an entire swimming pool?
--Patrick
No need to scrape or swab..evidently this much spit will usually provide enough cheek cells and other dna carrying cells for replication and typing.
(Incidentally, my co-worker shows me xkcd all the time--i must be one of the few geeks who finds it profoundly unfunny)