116 A MANUAL OF MENDELISM 



shall proceed first of all on the assumption that there 

 are three pairs of factors, namely, three dominants 

 producing red and their three recessives producing 

 white. If the assumption fails, we can try another. 



If there be three pairs of factors, with the three 

 dominants producing red grains and the recessives 

 white, then the 64 possible combinations among the 

 hybrids' progeny should consist of the following different 

 kinds : 



37 reds producing reds only 



8 reds producing reds and whites in the ratio 63 : 1 

 12 reds producing reds and whites in the ratio 15 : 1 



6 reds producing reds and whites in the ratio 3 : 1 



1 white producing whites only. 



These being the proportions in which the different kinds 

 should appear in 64 cases, then the 78 red lots bred from 

 should have consisted approximately of the following 

 kinds and numbers : 



45 reds producing reds only 



10 reds producing reds and whites in the ratio 63 : 1 



15 reds producing reds and whites in the ratio 15 : 1 



8 reds producing reds and whites in the ratio 3 : 1 



It will be noticed that there was no white-grained 

 plant among the 78 whose seeds were sown. One such 

 should have appeared in every 64, yet in 78 none 

 appeared. This is a result which must occur frequently 

 when the chances of the white grain appearing are so 

 small. 



It must be pointed out, before giving the actual results 

 of breeding from the above 78 lots, that it will be 

 impossible to say with absolute certainty to which 



