THE PITUITARY BODY 



moval of all parts of the pituitary body is the result of the 

 removal of the antagonistic influence of the pars tuberalis.^ 

 According to Jores and Caesar (1935), pigment of the 

 retina of the frog's eye assumes the dark position at a more 

 rapid rate, if the eye be treated by a solution of the "melano- 

 phore hormone" in the dark. Similar treatment of the eye 

 in the light only rarely is followed by an effect. Hypophysec- 

 tomy, however, does not alter the movement of retinal pig- 



TABLE 8 



The Effects of Extirpation of Various Divisions of the Pituitary 



Body on the Condition and Response of the Dermal Melano- 



PHORES IN Xenopus laevis* 



* From Hogben and Slome, Proc. Roy. Soc, London, B, 120, 158-73 (1936). 



t The higher the melanophore-index, the greater the degree of dispersion of the melanosomes, i.e., 

 the greater the "expansion" of melanophores. 



ment in response to light or darkness in either frogs (Jores 

 and Caesar, 1935; Matuo, 1935) or toads (Okamato, 1937). 

 Dubois-Poulsen (1937) also agreed that chromatosome-dis- 

 persing hormone facilitates the wandering of retinal pigment 

 into the position characteristic of darkness." The author 

 used frogs {Rana temporarid) and concluded that epinephrine 

 less effectively produces a change in the opposite direction. 



* The authors also investigated the manner in which optic stimuli affect the 

 background response. They concluded that the behavior of the melanophores of 

 toads on white or black backgrounds depends upon retinal localization. 



^ See also Matuo (1935). 



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