i^^5] Goodspeed: Germination of Tobacco Seed 247 



germination probably would have continued would have considerably 

 exceeded even the extended period characteristic of 30/06. 



The germination of hybrid seed was again undertaken this past 

 year partly in the expectation that the Fo, F^, and F^ seed might give 

 some evidence of such segregation as was observed to take place among 

 the plants grown from this seed. Thus it seemed possible that of the 

 seed produced by a given F., plant a distinct portion might germinate 

 early in the germination test and other portions have maxima of germi- 

 nation on later dates. It was then planned to grow separately plants 

 from the seed that germinated in considerable amounts at distinct 

 intervals in the test. Such groups of plants would be expected to be 

 similar within themselves and distinct from other groups. It is evi- 

 dent that seed of the various pure lines of Nicotiana described in this 

 and the previous report either complete their germination within three 

 or four days with little or no scattering germination before or after 

 this period of maximum germination, or that a few seeds germinate 

 early in the test and their number increases on succeeding days until 

 the maximum is reached, after which there is a corresponding gradual 

 decrease in the number that germinate until germination is at an end. 

 In only one case, 72/05, are there two unconnected maxima of ger- 

 mination, and in this case the corresponding situation evidenced by 

 the seed of F^ H 46 was assigned to the influence of this 72/05 parent. 

 The germination of the Fg and F^ seeds of H 46 and H 47 (tables IV 

 and V) realize, in some degree, the expected differentiation among the 

 seeds produced by hybrid plants of F^ and later generations. F^ H 24 

 P34 P23 and F3 H 23 P^g P04 Pi, for example, show breaks in the con- 

 tinuity of germination which are hardly as distinct in the germination 

 of any of the pure lines of Nicotiana tested with the exception of the 

 peculiar germination of N. acuminata varieties elsewhere noted (1913, 

 pp. 207 and 210). The evidence did not, however, seem sufficiently 

 conclusive to make it desirable to grow plants from the seedlings 

 produced at different periods during the germination tests. 



