12 



The Plant World. 



longed to the maternal parent and in others to the paternal 

 parent. The results of these reciprocal crosses were precisely 

 the same in both the 1st and 2nd hybrid generations of offspring. 



Seventy-four plants of the 1st hybrid generation were grown 

 to maturity and bore fruit. The general shape of the fruit was 

 oval, oblong or roundish, depending on the parentage, and was 



P"~ r 



Fig. 1. Types of foliage oceuring in P 2 hybrids of the potato leaf (solauopsis) 

 — cut leaf (csculcntum) cross. 



in every case intermediate between the two parents. However, 

 not a single plant of the F { generation bore fruit with the slight- 

 est semblance of a neck, hence there was complete dominance 

 of no neck (roundish fruit) over neck (pear shaped fruit). The 

 intermediateness noted for general shape outlines obviously has 

 nothing to do with the pair of characters under consideration. 

 In crossing many-celled or large fruited varieties with two-celled 

 or small fruited sorts (pear varieties belong to the latter class) 

 the two-celled condition is dominant in the first generation of 

 hybrids but there is a blending or intermediateness in size. Now, 

 in crossing pear varieties with large, round sorts the size of the 

 latter is so reduced, especially in transverse diameter, that re- 

 gardless of the fact that this hybrid fruit is without neck, it must 

 be classed as oblong or roundish. Three of the crosses under 



