472 COBB AND BARTLETT: INHERITANCE IN OENOTHERA 



Tables 3 and 4 present the data showing segregation into f. 

 typica and mut. formosa in the F2 generation grown from four 

 self-polHnated /j'^'ca individuals of the cross mut. formosa ^X 

 mut. latijolia C. In table 3, which is based upon the classifica- 

 tion of seedlings, the only distinction is between flat-leaved indivi- 

 duals (mostly f. typica) and revolute-leaved {mostly rmxt. jormosa) . 

 The difference between the two types of leaves is perfectly clear in 

 very young seedlings, though the different revolute-leaved muta- 

 tions are not easily distinguished from one another, nor some of 

 the flat-leaved mutations from f. typica, when very young. The 

 cultures were too large to be carried to maturity as a whole, but 

 the seedling classification was verified by growing to maturity a 

 sufficiently large number of the plants. 



Table 4, based upon the plants which were under observation 

 throughout the entire life cycle, shows that there was no signi- 

 ficant error in the classification of table 3. The revolute-leaved 

 plants were all correctly identified as mut. formosa, and among the 

 flat-leaved plants there was only a negligible proportion of muta- 

 tions. The ratio of flat to revolute conforms to the simple 3 : i 

 Mendelian ratio. The deviations from expectation are very 

 slight, and fall on both sides of the theoretical ratio. The total 

 progeny of each one of the four parents is in quite or almost as 

 good agreement with expectation as is the sum of all four pro- 

 genies. The total of 6,392 plants, from four parents, gives the 

 ratio 744 : 256, in unusually good accord with the expected ratio 

 750 : 250. 



The reader will notice that the mean germination is only 41 

 per cent, and that although the germination of the several cul- 

 tures varies from 4 per cent to 84 per cent, the ratio is neverthe- 

 less not seriously disturbed. The probability is therefore great 

 that we are dealing with a case of simple Mendelian inheritance, 

 uncomplicated by selective elimination of zygotes. Incidentally, 

 the results should tend to reassure anyone who may have feared 

 that the work with Oenothera is in general unreliable, on account 

 of the low germinations frequently recorded. 



