SIMILAR EFFECTS 117 



group some of them belong. For instance, if a lot 

 produce 100 red grains and no white, whether does 

 it belong to the red group giving no whites or to the 

 group giving reds and whites in the ratio 63 : 1 ? 



Or, if a variety produce 60 grains all red, to which 

 of the first two groups is it to be allotted ? If a variety 

 produce 30 or 40 red grains without a white, it belongs 

 neither to the 15 : 1 nor the 3 : 1 group ; but we cannot 

 say whether it belongs to the 63 : 1 or to the group 

 producing red only. If a variety produce 10 red grains 

 and no whites, it does not belong to the 3 : 1 group, 

 but we cannot say to which of the other three it belongs. 

 Thus we are compelled to rely upon the results in the 

 3 : 1 and 15 : 1 groups together with what assistance 

 may be afforded by the remainder. With this object 

 we shall arrange the results in groups as set out on 

 page 118. 



Then we see that the numbers in the 3 : 1 and 15 : 1 

 columns are very close indeed to expectation. So also 

 are those in the 63 : 1 column, upon which, however, 

 we cannot lay much stress, because some of the lots 

 in the previous column — more especially 30, 31, and 

 63 — probably belong to this or even to the 15 : 1 

 column. In any case, two critical groups are so close 

 to expectation that we may now conclude that the 

 wheats with which we have been dealing carry three 

 pairs of factors, namely, three dominants producing 

 red and their three recessives producing white. And, 

 since many of the red grains contained only two 

 of the factors for redness and a smaller number only 

 one, it follows that the red colour may be pro- 

 duced by any one of these, by two, or by all three 

 together. 



