122 DEVELOPMENT OF THE FROG'S EGG [Cir. XI 



non-injured side, whole embryos of half-size, but he believes 

 that at first there formed a half-gastrula, then a half-embryo. 

 Later this half-embryo completed itself without using material 

 from the injured side! That is to say, b}^ using "wandering 

 cells " the half-embryo has jjosfgenerated ^he other half of its 

 body ! 



