STOUT: INACTIVATION OF INCOMPATIBILITIES 



47 



even rudimentary capsules while the reciprocal relation of 2n X 4n resulted in 

 large capsules and many seed. But it may now he stated that of several seed 

 plantings involving large numbers of these seeds not one seed has germinated 

 and also that all of these seeds thus far examined have been without embryos. 

 There is therefore not a one-way inter-fertility or "compatibility" but an inter- 

 group sterility barrier between 2n plants and their derived 4n plants that is 

 of a status already well known for 2n populations of certain species, in which 

 there are no self- and cross-incompatibilities, and the derived 4n. That this 



Figure 1. Typical plants grown from seeds and of same age from seed planting; 

 in 7 inch pots. At left, self-incompatible diploid plants of Petunia axillaris. At right, 4n 

 P. axillaris of the second generation after induced autotetraploidy. The two large cap- 

 sules shown against the inserted card are such as are obtained to all self- and intra-cross 

 pollinations of the 4n population. 



