HYBRIDIZATION AND EARLY DEVELOPMENT 



357 



RECORD OF THE EXPERIMENTAL DATA FROM HYBRID CROSSES 



* Condition refers to any variables concerning either of the gametes such as prior irradi- 

 ation with x-rays, or ageing of the eggs, etc. 



NCUBU. JIOTOCMORO 



OP' jaiic •*ru>» 



Embryo formation in normal development and in the piplens 9 X sylvatica </* 

 hybrids. 0, M, S, and H represent tlie cells of the invaginating material that 

 will ultimately be found adjacent to the olfactory org,an, mouth, sucker, and 

 heart. OLF, olfactory organ; OPT, optic vesicle. 



Moore (1946) has found that in hybrids between Rana pipiens females and 

 Rana sylvatica males that development is normal to early gastrulation. The 

 arrested gastrulae remain alive for a number of days, and show restricted in- 

 vagination of the dorsal lip region. This is illustrated in the accompanying 

 diagreims. 



(From Moore l^hG: Jour. Exp. Zool. 101:175) 



