INTRODUCTION 



chameleon. Pouchet, however, showed still further that 

 if the spinal cord of a fish is cut, no such integumentary 

 darkening follows. This response took place only when 

 the sympathetic chains situated one on either side of the 

 vertebral column were severed. 

 He therefore declared that the 

 chromatophoral system was not 

 only under the control of nerves 

 but that these nerves were sym- 

 pathetic in origin. This con- 

 clusion has been abundantly 

 confirmed by a large number 

 of investigators, among whom 

 the chief is von Frisch (1910, 

 1911, 1912^, 1912^) whose 

 studies on the color changes in 

 fishes were published about the 

 beginning of the second decade 

 of this century and were a bril- 

 liant continuation of the mas- 

 terly work of his predecessors. 



But even before this time, 

 as von Frisch himself recoo-- 



o 



nized, a new current of ideas 

 had set in. This resulted from 

 a series of incidental obser- 

 vations the significance of which 



was not at first fully appreciated. In 1898 Corona 

 and Moroni showed that when adrenalin, the secre- 

 tion of certain cells in the medulla of the adrenal 

 gland, was introduced into the circulation of a frog the 

 pigment in its melanophores became strongly concen- 

 trated. This unique observation was confirmed by 

 Lieben in 1906 who made an extended investigation of 

 the subject. Comments by Fuchs in 19 14 on these two 



Fig. 



Turbc 



which particular nerves 

 have been cut wherebv 

 the melanophores of the 

 denervated regions have 

 been induced to disperse 

 their pigment thus ren- 

 dering the fishes dark in 

 those regions. Pouchet, 

 Jour. Anat. Physiol. , 

 1876, 12, pi. 4. 



