II 



MENDEL'S LAW 



The first result of Mendel's experiments was to reveal 

 the extraordinary regularity with which hybrids breed, 

 as manifested by the following observations : 



(1) The number of groups or kinds in the hybrids' 

 progeny is doubled with every additional pair of 

 characters in which the original parents differ. 



(2) The numbers of individuals in the several groups 

 can be arranged in the series (3 + 1)" where n stands 

 for the number of pairs of characters in which the 

 original parents differed. 



(3) The characters borne by the several groups 

 represent all the possible combinations in which the 

 parental differentiating characters can be combined, 

 consistent with the action of dominance. 



(4) Each group in a set of hybrids' progeny contains 

 equal numbers of constant or true-breeding individuals. 



It now became Mendel's task to discover the law by 

 which this regularity is determined and to formulate it 

 in words ; and this he did in the following statement : 



" The results to which the foregoing experiments led 

 were the cause of further experiments so designed that 

 conclusions might be drawn from them as to the nature 



12 



