blood sites?

[onomastikon]

I saw a mention of "blood sites" in the manual (forget where) -- I have never reserached the blood school and have ignored blood up till now because I dont want to upset my people searching for slaves and havent played a race with blood magic yet, but think -- hey, if there is a magic blood site you can find that puts blood slaves in your lab like gems, that must be ok. Can they be found like other sites? But then again, how does that work?

Also, I am playing Pangaia now and liking it, and was wondering whether to experiment with that Pandemonic guy (forget his name, nature 3 and blood 2 or something) -- can he find blood sites? Or just blood slaves? And is there any info on how this blood slaves work? Do you put them in your personal gems stack like jewels?

thanks