HEREDITY 189 



the dominant character, but also individuals which presented the 

 recessive character. Such a fact also was known in a jijood many 

 instances. 35ut IMendel discovered that in this generation the numer- 

 ical proportion of dominants to recessives is on an average of cases 

 approximately constant, being in fact as three to one. With very 'on- 

 siderable regularity these numbers were approached in the case of 

 each of his pairs of characters. 



"There are thus in the first generation raised from the cross- 

 breds seventy-five per cent dominants and twenty-five per cent re- 

 cessives. 



"These plants were again self-fertihzed, and the offspring of each 

 plant separately sown. It next appeared that the offspring of the 

 recessive remained pure recessive, and in subsequent generations never 

 produced the dominant again. 



"But when the seeds obtained by self-fertilizing the dominants were 

 examined and sown it was found that the dominants were not all alike, 

 but consisted of two classes: (1) those which gave rise to pure dom- 

 inants, and (2) others which gave a mixed offspring, composed partly 

 of recessives, partly of dominants. Here also it was found that the 

 average numerical proportions were constant, those with pure domi- 

 nant offspring being to those with mixed offspring as one to two. 

 Here it is seen that the seventy-five-per-cent dominants are not really 

 of similar constitution, but consist of twenty-five which are jnire 

 dominants and fifty W'hich are really cross-breds, though, like the 

 cross-breds raised by crossing the two original varieties, they only 

 exhibit the dominant character. 



"To resume, then, it was found that by self-fertilizing the original 

 cross-breds the same proportion was always ai)|)roached, namely: 

 25 dominants, 50 cross-breds, 25 recessives, 

 or ID : 2DP. : IR. 



"Like the pure recessives, the pure dominants are thenceforth 

 pure, and only give rise to dominants in all succeeding generations 

 studied. 



"On the contrary the fifty cross-breds, as stated above, have 

 mixed offspring. But these offspring, again, in their iiunicrical jiro- 

 portions, follow the same law, namely, that there are three ilominants 

 to one recessive. The recessives are pure like those of the last genera- 

 tion, but the dominants can, by furtlicr s(»lf-fertilization. and exam- 

 ination or cultivation of the seeds j)roduced, be again shown to be 

 made up of pure dominants and cross-breds in the same proportion 

 of one dominant to two cross-breds. 



