PLATE 2 



EXPLANATION OF FIGURES 



6 A 3-cell stage showing the unequal distribution of the chromatin between 

 the A and B cells. 



7 Showing the tetraster in the Si blastomere. 



8 Showing the tetraster in the Si blastomere. 



9 Showing normal 2-cell division after treatment with CO2 



10 Showing the A and B blastomeres dividing in abnormal planes. 



11 Showing the result of the division when the A and B cell occupy abnormal 

 positions. 



3cS2 



