Mendelism 



the case of what he called alternating characters, 

 that only one or other of the pair can appear in 

 the offspring, that they will not blend. If both 

 parents display one of the opposing characters, 

 the offspring will of course show it. But if one 

 parent display one character and the other the 

 opposing character, the hybrid offspring will dis- 

 play one only, and that which is dominant. The 

 other character is suppressed for the time being. 

 When, however, these hybrids are bred inter se, 

 their gametes or sexual cells split up into their 

 component parts, and then the recessives are free 

 to unite with other recessives and thus produce 

 offspring which show the recessive character. 



His results can be set forth in symbols. 



Let T stand for the tall form and D for the 

 dwarf form. Since the offspring are composed 

 of both the paternal and maternal gamete, we 

 may represent them as TD. But dwarfness is, 

 as we have seen, recessive, so that the offspring 

 all look as though they were pure T's. When, 

 however, we come to breed these TD's inter se, 

 the gamete or sex-cell of each individual crossed 

 breaks up into its component parts T and D, 

 which unite with other free T or D units 

 to form TD's or TT's or DD's. What are 

 the possible combinations ? A D of one parent 

 may meet and unite with a D of the other 

 parent, so that the resulting cells will be pure 

 D, i.e. DD, and will give rise to pure dwarf 



