§5.411 



BALANCE OF CALCIUM 



245 



seasonal effects upon ovary maturation (Zwarenstein and Shapiro, 

 1933), since the two are correlated in time; but the evidence on 

 the role of hypophysial hormones is almost as obscure here as it is 

 in fish. 



Table 29. Effect on blood calcium of injection of hypophysial 



HORMONES into XENOPUS 



Injections of histamine had no effect on the calcium content of serum 

 measured to within 04 mg% (from Shapiro and Zwarenstein, 1933). 



* 1 cm^ each of Parke Davis preparations. As these were mammalian 

 extracts, the Antuitrin would contain ACTH and TSH, of which the 

 latter could exert an indirect effect (see text). The Pituitrin would 

 contain ADH but probably no intermedin, though possibly ACTH 

 contamination. 



It has been claimed that the hypophysis can secrete two hor- 

 mones with opposing actions upon the serum calcium; that from 

 the PARS tuberalis of the hypophysis (§ 2.112) increasing the 

 calcium, and that from the neurohypophysis decreasing it slightly 

 (Shapiro and Zwarenstein, 1933). The structure of the pituitary 

 body of Xenopus is such that its parts can be readily separated and, 

 after removal of most of it, the pars tuberalis alone will regenerate ; 



