Serena walked in and held up some of her notes. "This is from some research I did in class, but the Professor never commented on it. Anyone have any more ideas?"

She lets them read her notes:

The spleen produces what are called antibodies, to fight infections or unfamiliar 'invaders' once they are detected. It also will swallow and digest debris in the blood such as worn out red blood cells and platelets and will also trap white blood cells. Maybe the rat spleen is used to fight the damaging effects that shrinking something could cause. It could help the body protect itself from the unfamiliar 'invader': the shrinking solution.