NOTES AND LITERATURE 



REPULSION IN WHEAT 1 



The evidence was furnished by the (F 2 ) of the cross: Smooth 

 Black X Rough White. " Smooth Black" is a wheat obtained 

 from the (F,) of the Rivet X Fife cross and it breeds quite true. 

 Its glumes are absolutely glabrous and of a burnished black color. 

 "Rough White" is the well-known Essex Rough Chaff Wheat. 

 The glumes are very hairy and of the ordinary white color. The 

 (F 2 ) sorted into the following classes: 



Rough Rough Smooth Smooth 



Black White Black White 



120 43 47 3 



The expectation for the 1 : 3 : 3 : 1 repulsion is : 



109.8 49.9 49.3 3.3 



"Blackness" is probably not a simple character for in the (F 2 ) 

 various degrees of it occur — the patches of it on the glumes being 

 of various sizes and intensities of color. There is evidence that 

 it is closely connected with the "gray" color of Rivet glumes. 



F. L. Engledow 



THE DETERMINATION OF THE BEST VALUE OF THE 

 COUPLING-RATIO FROM A GIVEN SET OF DATA 1 



Mr. G. N. Collins has suggested in this journal 2 a general 

 method for determining the value to assign to the coupling-ratio 

 for a given set of data. He has worked out the value of a coeffi- 

 cient of association for the whole series of possible integral ratios 

 1:1:1:1, 2:1:1:2, etc., and then used the observed value of the 

 same coefficient to decide which ratio gives the best agreement 

 with the facts. The method is very simple, but does not lead to 

 the value which is the most advantageous in a certain sense. If 

 F » F 2, F 3 , F 4 , are the set of theoretical frequencies for a given 

 value of the ratio and if F/, F 2 ', F 3 ', F 4 ', are the observed fre- 



*"A Case of Repulsion in Wheat," by F. L. Engledow, St. John's Col- 

 lege, Cambridge (Proc. Camb. Phil. Soc, Vol. 18). 



*F. L. Engledow and G. Udny Yule (Proc. Cambridge Phil. Soc, XVII, 

 436). 



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