THE INFLUENCE OF WATER AND LIGHT AND THE PITUITARY UPON THE PIGMENTARY SYSTEM OF THE COMMON TOAD (BUFO BUFO BUFO)

1. Bufo bufo bufo shows no melanophore response to moisture. 2. The severance of the optic nerve or the removal of the eyes causes a cessation of secondary responses to illuminated background. Some melanophore activity remains. 3. The cauterization of the optic chiasma or the infundibular stalk brings about the permanent expansion of the melanophores. 4. Hypophysectomy, and cauterization with hypophysectomy, both produce permanent contraction of the melanophores. 5. The implications of these results in relation to chromatic control are discussed.