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POPULAR SCIENCE MONTHLY 



wr 



Fig. 5. Rosette of Raimannia odorata. 



The seeds secured from such mutants should be sown as directed 

 above, and as many individuals as possible secured for comparison with 



the parental type, which should 

 be continued as before. If now 

 the individuals of the mutant 

 progeny are placed in a series 

 with respect to any given quality, 

 statistical observations may show 

 whether it is included within the 

 range of fluctuating variability 

 of the parental type. The ques- 

 tion therefore as to whether a 

 plant is a continuous or discon- 

 tinuous variant is one of simple 

 measurement and estimation of 

 qualities, not a matter of opinion. 

 With that simple question easily dis- 

 posed of, the investigator may next turn his attention to the correlations, 

 a phase of the question of vivid interest, since the sparse data at hand 

 seem to point to a wider range of variation and less degree of correla- 

 tion in such mutants than in the parental type. That is to say, instead 

 of mutants being derived from forms showing widely fluctuating varia- 

 bility, we have them appearing in the progenies of species in which the 

 range of variation is small and the correlations close, while the deriva- 

 tives themselves swing through a wide range of fluctuations. 



As a complementary means of 

 investigation of the constancy and 

 independence of the various char- 

 acters dealt with in selection and 

 mutation as observed above, hy- 

 bridization forms an invaluable 

 means of analysis, and is to be 

 constantly resorted to in all stages 

 of the various phases of the work, 

 since in the observation of the be- 

 havior of unit-characters in com- 

 bination and after resolution the 

 clearest appreciation of their char- 

 acter may be reached. 



Still another phase of variability 

 is that in which the greater portion 

 of an individual will be found to comply with the requirements of a 

 continuous series, but which bears a branch or portion of a branch which 

 differs notably by the loss or acquisition of characters. Although all 



Fig. 6. Rosetta of Mitant of Raimaii- 

 nia odorata induced by Chemical Tbeat- 

 ment of Ovules. 



