PEAS AND BEANS 143 



visional explanation of the observed facts might 

 be found in supposing that a dominant factor 

 when mated with a recessive one hides or ob- 

 scures the recessive one in that particular com- 

 bination, but does not eliminate it. 



And when the factors are again mixed to pro- 

 duce a new generation, they are still equal in 

 number, and if we think of the factors as tan- 

 gible things — let us say like black or white 

 checker men — it will appear that if equal numbers 

 of each are mixed together and taken from a bag 

 in pairs at random or blindfold, it will come 

 about, according to the mere theory of chances, 

 that one time in four two of the white checkers 

 will be paired. 



This accounts in a crude and mechanical but 

 on the whole a rather satisfactory way for the 

 appearance of the recessive character — say short- 

 ness of vine or greenness of pod — in one indi- 

 vidual out of four of the second-generation 

 progeny. 



And when we apply the same reasoning to the 

 case where two pairs of factors are under con- 

 sideration — tallness versus shortness, and yel- 

 lowness versus greenness in the present case — 

 it appears that each pair of factors will follow 

 precisely the same law, so that one in four of the 

 second generation descendants will be short and 



