THE PITUITARY BODY 



phores, xanthophores (or xantholeucophores), erythrophores, 

 and guanophores (iridocytes). Xanthophores and erythro- 

 phores are sometimes classified together as hpophores. The 

 most consistent effects of the hormone of the pars intermedia 

 are on the chromatophores of amphibia. In animals of this 

 class the hormone causes a dispersion ("expansion") of the 

 melanin-granules (melanosomes) and an aggregation or con- 

 centration ("contraction") of the pigment granules of the 

 xantholeucophores. In fish the effects vary in different 

 species. In reptiles changes in the chromatophores have not 

 been shown to be related to any internal secretion of the 

 pituitary body. 



The effects oj hypophysectomy or of extracts of the pituitary 

 on the chromatophores of fish. i. Hypophysectomy. — After the 

 removal of the neuro-intermediate lobe from the elasmo- 

 branch fish, Mustelis canis^ there occurs a pallor of the skin 

 due to the concentration of the melanosomes in the central 

 part of the melanophores (Lundstrom and Bard, 1932). This 

 effect is not produced by the removal of the pars glandularis 

 or by injury of the hypothalamus. The reverse effect, darken- 

 ing of the skin, is caused by the injection of extracts of the 

 posterior lobe including an extract with pressor effects 

 ("Pitressin") but not one containing chiefly the oxytocic 

 principle ("Pitocin"). Lundstrom and Bard concluded that 

 the control of the melanophores in this fish was a function of 

 the neuro-intermediate lobe and that (the sympathetic nerv- 

 ous system as well as) tissue secreting epinephrin'' probably 

 played no important part as a supplementary controlling 

 agency. 



Matthews (1933) hypophysectomized a teleost fish, Fundu- 

 lus heteroclittis, without affecting the chromatophore response 

 to various backgrounds and to darkness. He concluded that, 

 perhaps in teleosts generally, the control of the chromato- 



^ In both fish and amphibia epinephrin generally causes a pallor of the skin due 

 to a concentration of the melanosomes. 



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