1912] Goodspeed: Nicotiana Hyhrids 107 



2. Seeming Correlation between Weights of Seed and Inher- 

 itance OF "Dominant" and "Recessive" Characteristics 



The fact that the "dominant" parent — X. Tabacum var.wiac- 

 rophylla — when self- (close) fertilized in 1907 produced seed 

 which was heavier than the seed produced in the same manner by 

 the "recessive" parent — N. Tabacum var. virginica — in both 1906 

 and 1907, seems to be significant when we consider the weights of 

 the seed produced by the cross between these two parents and 

 when we consider the appearance of the F, generation produced 

 from the various weights of the hybrid seed. For the heavy 

 portion of the seed produced by self-fertilizing the hybrid 

 between macro phylla and virginica gave F„ hybrid plants of 

 which 39 per cent more closely resembled the macrophylla parent 

 than they did the virginica parent. Secondly, among the plants 

 produced by this heavy hybrid seed only 9 per cent resembled 

 virginica. Again, from among the lighter weights of the Fj 

 generation hybrid seed there were produced, as Fg generation 

 hybrids, 33 per cent of plants resembling virginica as against 

 18 per cent resembling macrophylla. Finally, from medium 

 weights of hj'brid seed there were produced approximately the 

 same percejntage of plants resembling macrophylla and re- 

 sembling virginica. 



Thus the parent of the cross .Y. Tahacum var. macro- 

 phylla $X ^^- Tabacum var. virginica (^ which possessed the char- 

 acteristic of bearing heavy seed is reproduced, more or less in- 

 tact, in the Fo generation grown from the heavy weights of the 

 Fi hybrid seed. Thus, again, the parent of the above cross which 

 is distinguished by bearing relatively light seed likewise appears, 

 more or less intact, in the Fo generation and is produced therein 

 from the lighter weights of F^ generation hybrid seeds. Finally, 

 the medium weights of F^ hybrid seeds gave plants in the Fa 

 generation approximately 50 per cent of which resembled N. 

 Tabacum var. macrophylla and 50 per cent resembled N. Tab- 

 acum var. virginica in appearance. 



