Witschi and McCurdy 



661 



TABLE 2 



Parabiotic Twins, Series jef-T {Ambystoma jeffersonianum-xTriturus torosus). 



F, normal ovaries; f, inhibited ovaries; M, normal testes; m, inhibited testes; i, indifferent gonads. 



The A.jefersonianiim was of the typical Iowa form in pair i and of a slightly dwarfed varietv 

 in all other pairs. 



No. 



I 



4 



5 

 6 



7 

 8 



9 



10 

 II 

 12 

 13 



Sex glands 



A. jej. 



F 



F 



M 



F 



F 



M 



M 



F 



M 

 F 



Triturus 



M 



f 



i(m) 



m 



i(m) 



i(0 



i(0 



i(m) 



F 



i(0 



i(0 



Age, 

 mo. 



13 



9 



9 



7 

 10 



4 



5 



3 



4 



5 

 5 



11ZC, mm. 



^. ;,./. 



98 



15 

 12 



19 

 I I 



24 

 21 



17 

 6.5 



18 



15 



Tritur 



41 



45 



48 



40 

 32 



44 

 40 



35 

 45 

 55 

 <;! 



TABLE 3 



Parabiotic Twins, Series tig-T {Amby stoma tigrinitmxTriturus torosus). 

 F, normal ovaries; f, inhibited ovaries; M, normal testes; m, inhibited testes; i, indifferent gonads. 



The A. tigrinnni member of pairs 1-8 is of the mexicanum variety, the one of pair 9 is of the 

 typical Iowa form. 



No. 



I 



2 



3 



4 



5 

 6 



7 

 8 



9 



Sex glands 



//. in 



F 



F 



M 



F 



M 



F 



F 



F 



M 



Triturus 



i(0 

 i(m) 

 i(m) 

 i 



i(0 



i(m) 

 i(m) 

 ilO 

 i(0 



Age, 

 mo. 



7 

 7 



9 



8 



12 



9 



16 



16 

 6 



Size, mm. 



36 



-5 

 8 

 21 

 24 

 19 



90 



Triturus 



19 



49 

 16 



53 

 22 



50 

 50 



50 



pairs (WitschP). The sex of Triturus cannot always be ascertained, though the 

 definite identification of eight females and fifteen males proves that also in the 

 newt there occurs no pronounced selective elimination. 



If, on the basis of the observations on controls, one might be tempted to 

 predict a leading role for the newt members, the actual results prove mark- 

 edly different from such expectations. As a matter of fact, a survey of the 

 entire material which is contained in condensed form in tables 1 to 3 shows 



