This study initiates research into the effects of IGF I on epimorphic appendage regeneration in the adult newt, Notophthalmus viridescens. As regeneration in this animal is often considered a recapitulation of development, the current research compares the expression of IGF I in developing larval forelimbs and regenerating adult forelimbs. To facilitate this comparison, a description of larval forelimb development was undertaken. This thesis is the first comprehensive record staging limb development in N. viridescens. In addition to the morphological descriptions, whole-mount and histological analyses of cellular development were made. This study determined that IGF I is a naturally occurring growth factor in this animal's liver, as observed among many vertebrates. ...