1912J Goodspeed: Nicotiana Hybrids 149 



diameters than the parents must again be noted in connection 

 with a recent report by Hayes (1912) and the discussion 

 therein given and the previous observations by Johannsen 

 (1906). 



The use of the term "fluctuation" throughout this paper has 

 been somewhat loose (Bateson. 1909. p. 210; cf. also, East, 1910, 

 p. 82) . In reference to the variations in corolla diameter exhibited 

 by the parental varieties of N. acuminata, the use of the word 

 "fluctuation" for such variation is undoubtedly valid. In using 

 the same term for the variations in corolla diameter of the hybrids, 

 a matter of convenience rather than .strict definition has been 

 con.sulted. It is probable that such a degree of variation in a 

 definite floral "unit character" as that shown by the fluctuation 

 in corolla diameter of the N. acuminata hybrids in Fj^, has never 

 been reported. That such great variation is due to "disturbing 

 effects .... of environmental origin" (Bateson, 1909, p. 239; 

 see also Hayes, 1912) is doubtful, and it is hard to see where the 

 results arrived at in connection with pure-line breeding are ap- 

 plicable (Johannsen, 1909). It is moreover clear that the in- 

 creased vigor generally assigned to the vegetative and floral 

 characters of hybrids (Groth, 1911, part I; East, 1909, pp. 174 

 and 177) is not the force compelling the great variation here, 

 for neither was the habit and foliage of the hybrid of a more 

 luxuriant type nor (and this is the important point) did the 

 hybrid corolla diameter in any case exceed by over one milli- 

 meter the diameter of the large-flowered parent in any cross. 



The last point we must take up refers to the purity of the 

 experimental parental material. To the best of my knowledge, 

 the three parental varieties of N. acuminata have come true to 

 certain definite corolla diameters for at least four years. Cer- 

 tainly during the past two years direct measurements have 

 shown that the three varieties are definitely distinguished from 

 one another by certain sizes of flowers, the fluctuations in the 

 corolla diameters of which are so small as to cause no inter- 

 grading of one variety into another. The probable existence 

 of the small-flowered variety as a wild type before its introduc- 

 tion into the Botanical Garden eight years ago, may suggest 



