266 Inheritance in the Groundsel 



Segregation took place as follows : — 

 For stem colour:— GG : Gg : gg :: 53 : 124 : 57 



For the ray character : — RR : Rr : rr :: 5S : 115 : 66 



The expectation in each case was :: 58 : 117 : 58 



But nine types should be present in the F^ generation. If these 

 occur in the expected proportion, we have a fair proof that there are 

 two pairs of factors and that they not only segregate normally, but that 

 the method of investigation is fairly accurate. Table XVI gives the 

 result of the analysis made from this point of view. 



TABLE XVI. 



RR Rr rr 



GG Gg gg GG Gg gg GG Gg gg 



Nos. found 10 30 13 28 57 SO 15 37 14 



Nos. calculated 15 29 15 29 58 29 15 29 15 



Differences -5 +1 -2 -1 -1 +1 +8 -1 



The approximation is as close as could be reasonably expected. 

 The greatest difference amounts to a divergence of 33 °/^. 



A similar result was obtained with the Fs generation of the cross 

 lanuginosus x erectus, the F^ parent plant having apparently the con- 

 stitution HHYYRrGg. The F^ generation in this case consisted of 

 92 plants, and the segregation proved to be as follows : — 



For the ray character: — RR : i2r : rr :: 23 : 52 : 17 

 For stem colour :— GG : Gg : gg :: 20 : ^8 : 24; 



For both characters, see Table XVII. 



When we consider the small number of plants experimented with, 

 the result agrees fairly well with the expectation. The deviations in 

 the types RRgg and rrgg are however worthy of note. They may mean 

 more than mere chance aberrations. Treating R and G as dominant, 

 the segregation appears as follows 



Found:— RG : rG 

 Calculated :—RG : rG 



Rg-.rg :: 54 : 14 : 22 : 2 

 Rg :r^:: 52 : 17 : 17 : 6 



