Alright guys, let's see if we can do a little bit of the giddy up for the learning as we go ahead and get her done right now. Yersinia's pestis. It was Yersinia's pestis in the kitchen with a knife. It's that bacteria that is the cause of plague. And that bacteria has existed for a long, long time. And the actual plague we're going to talk about is going to really be centralized in Mongolia and it's going to spread outward from there. But basically this is a bacteria that exists in various rodent populations, some cute, some not so cute like the black rat.