ENDOCRINE CO-ORDINATION 133 



for reasons stated above this is not a sufficient reason for 

 believing that the melanophores are under nervous control. 

 In tadpoles injection of extract or feeding with substance 

 of pineal gland produces an extreme condition of pallor 

 (McCord and F. Allen). But this reaction does not appear 

 to be shown by urodele larvae, in which the effects of removal 

 of the pineal (Laurens) on colour response were found to be 

 negligible. It is of interest to note that pituitary extract does 

 not produce expansion in the chromatophoresof the chameleon, 

 and in the melanophores of the Atlantic minnow, Fundulus, 

 Spaeth found that it produced contraction. The substance 

 in pituitary extract which produces expansion of amphibian 

 melanophores has recently been shown by Dreyer and Clark 

 to be different from the substances which are responsible 

 for the mammalian pressor and uterine responses. 



A group of phenomena of general biological interest that 

 appear to be subject to endocrine control are illustrated by 

 the cyclical activity of the genital ducts (secretory and muscular) 

 in the female of mammalia and their behaviour during the 

 several of gestation. Some advance has recently been made 

 by the discovery of Allen and his co-workers (1924) that 

 definite changes follow the injection of liquor folliculi into 

 ovariotomised rodents. In young rodents removal of the 

 ovary inhibits the growth of the genital ducts, and in older 

 animals produces degenerative changes in the latter with 

 cessation of cycHcal oestrous changes. When fluid contained 

 in the ovarian follicle of the normal individual is repeatedly 

 injected into a spayed female accelerated growth and secretion 

 characteristic of the oestrous cycle are induced. 



Further References 



ScHAFER. The Endocrine Organs. Longmans, Green. 

 HoGBEN. The Pigmentary Effector System. Oliver and Boyd. 

 Swale Vincent. Internal Secretion of the Ductless Glands. Arnold. 



