OENOTHERA RUBRINERVIS, A HALF MUTANT. 



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nervis. Part of the seeds of the original mutant of 1895 had been 

 preserved until 1905; they germinated sufficiently and gave the 

 second generation. From this a third generation was derived in 

 1910, 1913, and 1914, and a fourth in 1913, 1914, and 1915. All 

 the parents of these generations have been artificially fertilized by 

 myself. In 1914 I observed for the first time a specimen of deserens 

 among these cultures, and this in a third generation. Thereupon 



I sowed in 1916 the self-fertilized seeds of 11 specimens in order to 

 decide whether all of them would repeat the splitting and to deter- 

 mine roughly the percentage of the new type. The results are given 

 in the table. From these figures we see that all the specimens tried 

 show the same splitting, and that this is always a mass mutation. 

 The countings for this table were partly made in the stadium of 

 the young rosettes and partly at the time of flowering. In order to 

 prove the correctness of this process, I repeated the sowings in 1917 

 for those of the parents of which sufficient seed had been preserved, 

 planted out all of their seedlings, and counted them in August, 

 when they were ripening their first fruits. The results are as follows: 



