PARS INTERMEDIA AND PARS TUBERALIS 



phores was chiefly nervous rather than humoral. ^ However, 

 as will be shown, the chromatophores of other teleost fishes 

 may change in response to pituitary extracts. 



2. The effects of extracts. — In several teleost fishes changes 

 in the chromatophores may follow the injection of extracts 

 of the pars intermedia or of the posterior lobe of the pitui- 

 tary. To what extent the formation of pigment and the con- 

 trol of the chromatophores depend on the pituitary is not 

 known except in Fundulus in which the pituitary appears to 

 be of little importance in regulating chromatophores. In 

 other teleost fishes the effects of hypophysectomy have not 

 been observed except, perhaps, in the experiments of Giers- 

 berg (1932). 



If isolated scales of the killifish, F. heteroclitus, are placed 

 in a solution containing an extract of the posterior lobe, the 

 melanosomes become concentrated in the central part of the 

 melanophores (Spaeth, 191 8; Wyman, 1924; and Matthews, 

 1933)- (Previous treatment of the scales in order to cause 

 melanosome dispersion may be necessary to demonstrate 

 clearly this effect.) Odiorne (1933) could detect no change in 

 the melanophores of Fundulus either after the injection of 

 posterior-lobe extract into the intact fish or by placing scales 

 in a diluted posterior-lobe extract. He also injected a pos- 

 terior-lobe extract into catfish {Amiurus nebulosus) without 

 subsequently observing any change in the melanophores. 

 In the pope (a member of the perch family, Acerina cernua) 

 and in Gobiofluviatilis the injection of a posterior-lobe extract 

 is said to be followed by a dispersion of the melanosomes 

 (Blanchard, Prudhomme, and Simmonet, 1932). Hewer 

 (1926) concluded from his studies in the minnow that 

 posterior-lobe extract causes a concentration of the melano- 

 somes (melanophores) but dispersion of the erythrosomes 

 (erythrophores) and xanthosomes (xanthophores). Recently 



s See also the reports of Parker and that of Fries (1931). 

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