A Generalized Example 253 



discussion of genie aetion within a differentiated cell or cells. It 

 should be added at this point that, unfortunately, no. individual 

 Mendelian mutants for umbrella characters are known in this alga; 

 hence the experiments deal only with the genome as a whole. 



These facts are further confirmed by experiments in which nucle- 

 ated pieces of two different species were combined and regenerated 

 as a common branch, presumably under the influence of both nuclei. 



5. Group 



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 crenomedi medocren, medoCrenQmed, 



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The regenerated umbrella was intermediate between the two species 

 (figs. 14, 15). When the difference between the species was greater, 

 the compromise regenerate was more or less abnormal, though show- 

 ing the mixture. Combinations of three pieces of which two had the 

 nucleus of one species, the third that of another species, point in the 

 same direction. The regenerated umbrella had more resemblance to 

 the species that had supplied two nuclei (fig. 15). Thus the quantity 

 of the determining stuff is related to its action. Finally (fig. 16), the 

 effects of those umbrella-forming stuffs were tested which had been 



