THE PITUITARY BODY 



pressor or the oxytocic principle (Hogben and Winton, 1922- 

 23; Dreyer and Clark, 1924; Houssay and Ungar, 1924; 

 Knaus, Dreyer, and Clark, 1925; Gaddum, 1928; Rowe, 

 1928; Hogben and Gordon, 1930; and Stehle, 1934). 



THE PARS TUBERALIS 



The pars tuberalis of the pituitary of the ox appears to 

 have no significant effect on either the uterus (contraction of 

 isolated uterus) or on the blood pressure (Atwell and Mari- 

 nus, 1918). Later (1927) Atwell found that the intravenous 

 administration of an extract of the pars tuberalis to the 

 anesthetized rabbit caused a diuresis which, unlike that due 

 to the vasopressor principle, was preceded by no short period 

 of anuria and was accompanied by no change in the blood 

 pressure. 



Hogben and Slome (1931) concluded from extirpation- 

 experiments that the white-background response oi Xenopus 

 laevis depends upon a secretion of the pars tuberalis. Fur- 

 ther, they inferred that in the hypophysectomized frog 

 (which is hypophysectomized except for the pars tuberalis), 

 the secretion of the pars tuberalis antagonizes the melano- 

 some-dispersing effect of pituitary extract. 



318] 



