TRAIT SIZE REGULATION. “The findings we describe bear on an old and still unanswered question in biology, namely, how the absolute and relative sizes of traits are regulated. Numerous experiments on regeneration and transplantation have shown that the final size of appendages and internal organs is regulated autonomously, within the structure itself; size regulation of body parts typically requires no external control.”
http://www.pnas.org/content/95/7/3685.full