in Hybridisation 343 



Half should have violet-red flowers (A a), Classes 

 white flowers (a) 



a long axis (B&) 



>, ,, a short axis (6) 



From 45 fertilisations of the second year 187 seeds 

 resulted, of which only 166 reached the flowering- stage -in 

 the third year. Among these the separate classes appeared 

 in the numbers following : 



Class Colour of flower Stem 



1 violet-red long 47 times 



2 white long 40 ,, 



3 violet-red short 38 



4 white short 41 



There subsequently appeared 



The violet-red flower-colour (Aa) in 85 plants. 

 ,, white ,, (a) in 81 ,, 



,, long stem (2&) in 87 ,, 



short (b) in 79 



The theory adduced is therefore satisfactorily confirmed in 

 this experiment also. 



For the characters of form of pod, colour of pod, and 

 position of flowers experiments were also made on a small 

 scale, and results obtained in perfect agreement. All 

 combinations which were possible through the union of 

 the differentiating characters duly appeared, and in nearly 

 equal numbers. 



Experimentally, therefore, the theory is confirmed that 

 the pea hybrids form egg and pollen cells which, in their 

 constitution, represent in equal numbers all constant forms 

 which result from the combination of the characters united 

 in fertilisation. 



The difference of the forms among the progeny of the 

 hybrids, as well as the respective ratios of the numbers in 

 which they are observed, find a sufficient explanation in the 

 principle above deduced. The simplest case is afforded 

 by the developmental series of each pair of differentiating 

 characters. This series is represented by the expression 

 A + 2Aa + a, in which A and a signify the forms with 

 constant differentiating characters, and Aa the hybrid for 



