are you talking about the plugs in the arms of the pod people? those are for, most likely, obtaining energy and waste from the blood stream...I do not KNOW EXACTLY what they are for, because that hasn't been described or explained, plus i'm not into Bio, so you might want to ask someone who is...The things i can think of for the plugs are: jacking brain into matrix directly, giving air, taking waste air, giving nourishment, taking waste, taking electricity, absorbing heat (although that would be out of the gel stuff, not off the body). So, perhaps the arm plugs are to inject water and some kind of nourishment into the blood stream (such as was done on the Neb) and for taking the waste from the blood stream and sapping the electricity off the body...