Why is there a bright green part mixed in with my chicken liver sometimes?

Found this answer from Jacques Peppin: http://www.jacquespepin.net/members/recipes/chickenliverpate.html Be sure that the livers are free of sinews and of any part that is green, which indicates that some of the bitter bile has been in contact with the liver. Pale yellow livers tend to have a mellow, rich taste and are preferable to deep red ones. http://www.jacquespepin.net/members/recipes/chickenliversvinegar.html The liver on the right is pale in color (our favorite), and the one on the left is darker and still has the little green bag, the gall bladder, attached to it. This bag (next to the point of the knife) should be removed, because the liquid inside (the bile) is extremely bitter. Sometimes it breaks when it is removed, and some of the liquid runs on the liver and makes it green. Any greenish part of the liver should be removed, because it will be very bitter.