1032 



A. W. BLACKLER AND M. FISCHBERG 



As to the nature of the dorsal and ventral surfaces of the hybrid toads, it is 

 clear that the peter si influence is dominant over that of laevis. In the development 

 of the eggs laid by the hybrids, one may recognise a Xll maternai effect and 01 

 dominance in the matter of the character of the third cleavage division and a 

 dominance concerning the stage at which melanophores make their appearance. 

 For the rest the size and type of egg, the time of appearance of melanophores on 

 the tail and the rectal tube région, appear ordered by the petersi component of the 

 génotype. 



Since in our laboratory we have been concerned with the transplantation oi 

 nuclei between Xlp and Xll (Ortolani, Fischberg and Slatkine, 1966), furthei 

 light on the nature of thèse toads has enabled a better appréciation of some of the 

 observations reported here. 



ACKNOWLEDGEMENTS 



We gratefully acknovvledge the assistance we have received in this study frorri 

 Misses Messinezy and Petersen, as well as the financial support of the Fonds Natio- 

 nal Suisse (No. 2551). 



REFERENCES 



Ahl. E. 1924. Ueber einige afrikanische Frôsche. Zool. Anz. 60: 270-1. 

 Blackler, A. W. 1962. Transfer of primordial germ-cells between two subspecies oj 

 Xenopus laevis. J. Embryol. exp. Morph. 10: 641-51. 



— Fischberg, M. and Newth, D. R. 1965. Hybridization of two subspecies Oj 



Xenopus laevis. Rev. Suisse Zool. 72: 841-57. 

 Bocage, Barboza du, 1895. Herpétologie d'Angola et du Congo, p. 187. 

 Daudin, F. M. 1802. Histoires des Rainettes, des Grenouilles et des Crapauds. 

 Gurdon, J. B. 1961. Transplantation of nuclei between two subspecies of Xenopus laevis 



Heredity 16: 305-15. 



— 1962. 77?^ transplantation of nuclei between two species of Xenopus. Dev. Biol. 5 



68-83. 



Loveridge, A. 1932. Proc. biol. Soc. Washington 45: 114. 



Nieuwkoop, P. D. and Faber, J. 1956. Normal Table of Xenopus laevis (Daudin) 



Amsterdam: North Holland Publ. Co. 

 Ortolani, G., Fischberg, M. and Slatkine, S. 1966. Nuclear transplantations betweei 



two subspecies of Xenopus laevis {Xenopus laevis leavis and Xenopu. 



laevis petersi). Acta Embryol. Morph. exp. 9: 187-202. 

 Parker, H. W. 1936. Reptiles and amphibians collected by the Lake Rudolf Rift ValleA 



expédition. Ann-Mag. Nat. Hist. 18: 596-601. 



— 1956. In Normal Table of Xenopus laevis, pp. 9-12. 



Schmidt, K. P. and Inger, R. F. 1959. Amphibians : Exploration du Parc National d» 

 VUpemba. Mission of G. F. Dewitt. Hist. Parcs Nation. Congo Belge 56 I 

 1-264. 



