EVIDENCE PROVING THE MELANOPHORE TO BE A 

 DISGUISED TYPE OF SMOOTH MUSCLE CELL 



REYNOLD A. SPAETH 



Osborn Zoological Laboratory, Yale University 



TWO FIGURES 



CONTENTS 



Preliminary 193 



Morphological evidence 194 



Embryological evidence 195 



Physiological evidence 196 



I. Innervation 198 



II. Effect of light 199 



III. Effect of electrical stimulation 200 



IV. Effect of mechanical stimulation 201 



V. Effects of chemical stimulation 202 



A. Inorganic substances 203 



B. Organic substances 207 



An analysis of the contraction in the melanophore 209 



General application of the conclusion ." 212 



Summary : 213 



Bibliography 214 



PRELIMINARY 



The melanophores of the lower vertebrates, fish, amphibians 

 and reptiles, are described by most authors as modified connec- 

 tive tissue cells (Fuchs '14). The evidence for such a concep- 

 tion rests chiefly upon a morphological basis. Leydig ('89, '92), 

 showed that no sharp morphological distinction exists between 

 unpigmented, connective tissue cells, inactive, pigmented con- 

 nective tissue cells and chromatophores (melanophores) con- 

 taining actively migrating pigment granules. 



During the past four years I have been carrying on a series 

 of experiments on the direct physiological responses of the 

 melanophores in fish, chiefly in Fundulus. These experiments 



193 



