EXPERIMENTAL MORPHOGENESIS 67 



the sole exception that there was a tendency of the 

 endoderm of the half-larva of Beroe to become more than 

 " half." But that was not what we chiefly wanted to 

 study. We succeeded in cutting away a certain mass of 

 the protoplasm of the ctenophore egg just before it began to 

 cleave, without damaging its nuclear material in any way : 

 in all cases, where the cut was performed at the side, there 

 resulted a certain type of larvae from our experiments which 

 showed exactly the same sort of defects as were present in 

 larvae developed from one of the first two blastomeres 

 alone. 



The hypothesis of the morphogenetic importance of 

 protoplasm had thus been proved. In our experiments 

 there was all of the nuclear material, but there were 

 defects on one side of the protoplasm of the egg ; and the 

 defects in the adult were found to correspond to these 

 defects in the protoplasm. 



And now 0. Schultze and Morgan succeeded in per- 

 forming some experiments which directly proved the 

 hypothesis of the part played by protoplasm in the subject 

 employed by Eoux, viz., the frog's egg. The first of these 

 investigators managed to rear two whole frog embryos of 

 small size, if he slightly pressed the two-cell stage of that 

 form between two plates of glass and turned it over ; and 

 Morgan, 1 after having killed one of the first two blastomeres, 

 as was done in the original experiment of Koux, was able 

 to bring the surviving one to a half or to a whole develop- 

 ment according as it was undisturbed or turned. There 

 cannot be any doubt that in both of these cases, it is the 

 possibility of a rearrangement of protoplasm, offered by 



1 Anat. Anz. 10, 1895. 



