The Pigmentary Effector System. VI. The Dual Character of Endocrine Co-Ordination in Amphibian Colour Change

摘要: In foregoing contributions to this series an attempt has been made analyse the process of co-ordination in a characteristic mode behaviour encountered Amphibia and Reptiles. It is now clearly established that pituitary gland essential agency determining Amphibian colour change. Accepting conclusion, it still possible entertain hypothesis secretion merely condition response melanophores nervous impulse efferent fibres supplying skin. The present investigation subject possibility more rigorous examination. direct innervation not by histological examination, time relations pigmentary effector activity do suggest intervention peripheral mechanism. As shown last communication series, Reptiles are directly innervated. Experiments on stimulation section nerve trunks have led investigators change ambiguous results, which extensively criticised elsewhere. chief source misunderstanding arises from fact nerves general contain vasomotor components. work chameleon demonstrate segmental effects origin, employing as stimulus generalised pallor for receptor surface localised. For further analysis becomes necessary undertake precise definition receptive field. A visual naturally suggests itself most convenient type purpose. European frog ( Rana temporaria ) various factors, including humidity temperature, significantly co-operate with illumination determine activity. South African clawed toad aquatic Anuran whose chromatic responses almost entirely determined photic stimuli. This circumstance explore problem thoroughly than previous researches recorded communications. Xenopus other Anura there three types organs. These epidermal melanophores, b dermal c xantholeucophores. important agents visible reaction. Their can easily be followed microscopic examination web. what ensues attention directed unless otherwise stated.