ALTERATION OF THE AXIAL GRADIENT. 



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dotted lines, on the original apical region of the old cell. The 

 arrows indicate the gradients. Death begins in the apical cell 

 of the new axis and continues down the large cell to its middle, 



8 



10 



while an opposed gradient exists at the opposite end of the large 

 cell. It is of course impossible to determine the physiological 

 history of this cell, but appearances suggest that the cell was 

 one of those in which the gradient had been reversed and a 



