1913] Goodspeed: Germination of Tobacco Seed 201 



upon which they appear, have been in part dealt with in a pre- 

 vious comnranication (Goodspeed, 1912). Recently, also, it 

 appears to have been shown that the hybrids made between N. 

 sylvestris and various N. Tafear/rm -varieties may be considered 

 to be partially fertile rather than completely sterile (Goodspeed, 

 1913), and this fact was brought to light both by a careful 

 examination of the relatively few seed capsules (unprotected) 

 that persist on these F^ hybrids and the germination under con- 

 trolled conditions of such little seed as was found within them. 

 Again it is always conceivable that the so-called ratios which 

 appear to be manifested in the results of breeding experiments 

 from the Mendelian standpoint on the plant side may be modi- 

 fied by, or possibly are directly dependent upon, a high or low 

 percentage of germination of the seed used to produce the plants 

 the outward appearance of which is to be reported upon. In 

 view of these several considerations, and especially that the more 

 or less technical details connected with the breeding experiments 

 reported upon in this volume may be entirely plain and that 

 certain of the fundamental factors with which we are dealing 

 in these experiments may be more thoroughly understood both 

 by ourselves and by others, a rather detailed report upon the 

 germination of the parent and hybrid tobacco seed used seems 

 justified. It is hoped that further studies in this connection now 

 being pursued may be reported upon in the near future. 



II. SEED USED 



As will be noted in the tables which follow, the seed used in 

 the germination tests herein reported upon was taken from 

 single plants representing the following species and varieties of 

 Nicotiana and various crosses made between them. The desig- 

 nations given refer to the acquisition number, the year first sown 

 and the hybrid number in the U. C. B. G. 



110/05— A^. Tabacum var. calijcina (Setchell 1912, p. 6). 

 22/07 — N. Tahacum var. macrophylla (ibid., p. 8). 

 78/05— N. Tabacum "Maryland" (ibid., p. 5). 

 78/09— 2V. attenuala (ibid., p. 24). 



53/03 — N. acuminata variety (ibid., p. 23, and Goodspeed, 1912, pp. 

 119-122). 



