1918] Goodspeed-Davidson: Controlled Pollination in Nicotiana 431 



Tabulated Results of Controlled Pollinations in Nicotiana Langsdorfjfii 

 VAR. grandiflora (U. C. B. G. 107/08w) 



Plant 17 was used as the pollen parent in each case. 



Position of seeds 



One seed in each cell ; one at top and one in 



middle. 

 Four close together near top of one cell. 



Middle. 



Three in one cell, one at bottom and two in 

 middle; four in the other cell, two at bottom 

 and two in middle. 

 21 48 3 3 One at bottom of one cell ; two in middle of 



the other cell. 



A number of points of interest which might repay further study 

 suggest themselves in connection with the results noted in the above 

 table. The present data is too fragmentary to make possible any 

 specific conclusions of general applicability. Such conclusions must 

 wait upon a greater accumulation of evidence to allow of statistical 

 treatment of the results. However, certain points brought out in the 

 above table bear directly upon the question of the total sterility of 

 the pollen of the Fj Tabacum-sylvestris hybrids and upon the general 

 abscission problem in Nicotiana. 



It is evident that fertilization of an extremely small percentage of 

 the ovules capable of fertilization- is sufficient to cause the flower to 

 be held upon the plant rather than to be abscissed. We have for some 

 time suspected that some such delicate balance existed between fer- 

 tilization and the activation or formation of the separation layer. In 



2 Over two hunrlred viable seeds are produced by close pollination in 

 Nicotiana Langsdorfjii var. grandiflora. 



