PLATE 1 



Figs. 4-7. Heterogenous parabiotic pairs. 



¥ig. 4^. Ambysto)7ia niaculaliun x white axolotl, one day after grafting opera- 

 tion; showing the stage at which union is established, x 8. 



Fig. 5. Two pairs {Ambystoma maculatum X Triturus torosus) showing the 

 reduction of the yolk sacs and formation of anastomoses between the abdominal 

 veins. The (longer) salamanders are paralyzed. X 5. 



Fig. 6. Another pair of the same combination at the time when feeding be- 

 comes established. The salamander (longer member) is coming out of the 

 paralyzed condition, x 4. 



"]. Ambystoma jefjersonianum X Triturus torosus, shortly after metamorphosis 

 (6 months old), x 1. 



[670: 



