618 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



To do this, we have selected the hybrid P. x Leeatmm (the product of 

 P. Spicerianum and P. insigiie), and have crossed it with the species 

 P. Boxallii. 



For the sake of convenience and brevity we will call P. Spicerianum, 

 S ; P. insigne, I ; P. x Leeanum, SI ; and P. Boxallii, V>. 



Our forty-nine hybrids of ' P. x Leeanum crossed with P. Boxallii will 

 therefore be SI x B. 



Now, if Mendel's theory be correct, the hybrid SI will form deter- 



