Oh good. They knew what he was talking about. At least most of them did. Some of the purebloods and the ones who were not really acquainted to the Muggle world were quite shocked to hear that the blood had to be taken from other Muggles. No, there was no blood replenishing potion in the Muggle world.

"Yes, the doctors in the hospitals who need blood for a patient normally get it from so-called blood banks, like some of you mentioned already. The blood banks get the blood from willing donors who have donated their blood in order for it to be used for exactly that, if somebody needs extra blood to survive." Awesome, eh?

"Now, unfortunately there are a few problems with this system, as not everybody's blood can be used for various reasons." Nodding at Helena who had first mentioned it, he added, "We had the problem that people can only receive blood of the same blood type as theirs. Any other possible problems?" Jeremy had turned to write 'different blood groups' onto the blackboard and was now waiting for more suggestions.