50 
GENETICS: SETCHELL ET AL. 
Proc. N. A. S. 
notes ineffective. I also constructed diapason pipes over 60 cm. long and 
5 cm. in diameter, which were excited with my adjustable embouchure. 
The full c' obtained had the same direct effect on the interferometer as 
the clarionette. This discrepancy is exceedingly difficult to eliminate as 
it calls for a detection of the resonant member of the interferometer. 
With the 1-foot diapason organ pipes used above, there is much less 
danger of direct influence. This is shown, for instance, in the balance 
obtained with nodes of opposite sign. Moreover, I made control experi- 
ments by blowing equipitched diapason pipes strongly in the neighbor- 
hood. There is even here liable to be a little response. The tendency to 
assume wave form may be recognized; but it is much smaller than the 
pipe note proper, and quite absent in the overtones. Finally, the elbowed 
pipe, figure 3, which blows away from the interferometer, was used for 
additional guarantee and for overtone nodes. 
A PRELIMINARY NOTE ON THE RESULTS OF CROSSING 
CERTAIN VARIETIES OF NICOTIAN A TABACUM 
By William Albert Setchell, Thomas Harper GoodspEEd and Roy 
Elwood Clausen 
Department of Botany and Division of Genetics of the Department of Agri- 
culture, University of California 
Communicated January 10, 1921 
In connection with a taxonomic study of the various species and varie- 
ties of Nicotiana, the authors became interested in the extremely varied 
assemblage of varieties, both botanical and commercial, included under 
the species N. Tabacum. The senior author ventured to suggest a prefer- 
ence for five type varieties as representative of the range of variation found 
within the species and possibly of fundamental importance as stem forms 
in the derivation of other varieties. A similar attempt to refer existing 
commercial varieties, to derivation from a limited number of fundamental 
forms had previously been made both by Comes 1 and Anastasia. 2 These 
authors agreed in principle on the method of derivation of existing varieties, 
but they held conflicting views as to which particular forms should be 
recognized as fundamental. In all three cases the principle followed in 
attempting to unravel the problem of origin of cultivated forms was to 
determine which few historically old varieties possessed in various com- 
binations all the characters exhibited by commercial varieties, and then 
to refer existing varieties to hybridization with resulting segregation and 
recombination of characters exhibited in the stem forms. 
The senior author, having tentatively selected five such stem forms, 
thought it wise by actual genetic experimentation to determine what 
results would follow hybridization among them. The authors also found 
themselves in need of some definite information as to the Mendelian de- 
