70 Mr. Darbishire. Experimental Estimation of the [Dec. 7, 



Pisum."* Subjoined is the table in which the details of this evidence are 

 summarised by Mr. Lock. I give it in full because it embodies the result 

 in F 2 from the cross made by Mr. Hurst, in F 5 from which the extracted 

 greens which I used in my experiment occurred. The percentage of greens 

 calculated from the total is 24*9. The actual deviation is less than the 

 Probable Error. 



Observer. 



Yellow. 



Green. 



Green, 



per cent. 





6,022 



2,001 



24 -9 



Correns 



1,394 



453 



24-5 





3,580 



1,190 



24 -9 





11,903 



3,903 



24 -7 





1,310 



445 



25 -4 



Lock 



1,438 



514 



26 "2 





25,647 



8,506 



24 -9 



Besides the above, I have some evidence based on observations made by 

 me which more strictly deserve to rank as control observations. This evidence 

 is based on the result of crosses made between the identical yellow races used 

 in the experiment, and, with the exception of the few crosses made in 1906, 

 from the pollen from the identical crop of plants which were the yellow 

 parents in the cross between the pure yellow and extracted (F 5 ) green (see 

 Table II). The details of the F2 families raised from these control crosses are 

 given in Tables VII and VIII. The total number of yellows raised was 

 4015, and of greens 1394, the percentage of greens being 25*77- The Probable 

 Error of the percentage is + - 401, so that the actual deviation, being less 

 than twice the Probable Error, is certainly not significant. 



The expense of carrying out this experiment was defrayed by a grant from 

 the Government Grant Committee of the Eoyal Society, and I take this 

 opportunity of expressing my indebtedness to them. I also wish to express 

 my thanks to Mr. Udny Yule and to Dr. E. Schuster for some preliminary 

 statistical assistance, and to Mr. Charles Biddolph for clerical help. 



Summary. 



An experiment has been devised to test the truth of the theory of Ancestral 

 Contributions : the results of the experiments prove : — 



(a) That the phenomena of dominance, and, what is more important, of 

 the segregation of characters in definite proportions, are independent of the 

 ancestry (and of the geographical source) of the parent-forms mated. 



* ' Annals of the Eoyal Botanic Gardens, Peradeniya,' vol. 4, Part Til, 



