AND INHERITANCE IN PEDIASTRUM. 437 



ganized. The direct effect of the mother cell vesicle in flattening 

 one or both edges of the plate (Figs. 18-24) in case of slightly 

 weakened colonies is typical of the effect of an unfavorable en- 

 vironment in limiting or inhibiting normal development. 



The relative perfection of arrangement of the peripheral and in- 

 terior cells is also most suggestive of the indirect effects environ- 

 mental conditions may produce. Statistical studies of the degree 

 of approximation of different colonies to the typical expressed in 

 terms of divergence of cell axes from the axes of the colony as a 

 whole, degrees of distortion of cell form, variation of the angles 

 of intersection of cell walls from 120°, etc., may be expected to 

 afford a reliable index of the effect of environment on the metab- 

 bolism and growth of the cells. 



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