TflK PROBLEMS OK HEiiKDITl AND TIIKFR SOLli^TlON. HCiG 



follow llicsuiiic law. iiaiiM'lx'. thai llici'c ai'c tliicc (loiiiiiiaiils to one 

 ic(t>>-i\ c. Tlic rcccssjvcs ill"*! purr like tliox' of the ia.'^t oc'iicrat ion. 

 but the (lominants fan, l)y furtlior sclf-fcrtili/ation. and examination oi- 

 cultivation of th<' seeds produced, he a^ain sliouii to be made up of 

 })ure dominants and (•i'ossl)i'eds in the same propoi-tion of one dominant 

 to two ci'osshreds. 



The process of breakine' up into the ])arent roi'm> is thus eontimied 

 in each sucf-essive o'Oiieration, the ssmie nuiin'rical law beine- followed 

 so far as has yet Immmi ()l)served. 



Mendel ma(h' further expei'imenis with /V.s////^ sat/ninii, ci'ossin(( 

 paii's of varieties which diti'ered fi'om each othoi' in two charact(!r,s, 

 and the results, thout^h ueces.sai-ily much moi'c complex, showed tluit 

 the law exhibited in the simpler cas(; of paii's dilferine- in respect of 

 one charact<'i- o})erated hei'e also. 



Jn the case of the union of \ai-ieties A I> and ah dili'ei-in<i; in two dis- 

 tinct j)airs of characters. J and <i. 11 and A. of whi<-h A an<l /> are 

 d<jminant. a and h recessive, Mend(d found that in the first crossbred 

 <reneiation there was (inly one class of offsprinj:', i-eally Aa Iil>. 



But b\' reason of the doiinnance of one character of each |)air these 

 first crosses wei'e hardly, if at all, distinj^-uishable fi-om Ali. 



\\\ lettino- these AaBh'^ fi'itilize tliemseh cs, only four classes of 

 oti'spi'ine- seemed to be piYxluced. nauxdy. 



Ali showinj^ l)oth dominant characters. 

 Ah showing dominant A and recessi\<' 1>. 

 (iB showing recessive a and dominant />. 

 (ih showing both recessive characters <i and h. 



The numei-ical proportions in which these (dasses appeared we ic also 

 legular and approached the ratio 



\)An : .", Ah : ?„i II : ).//.. 



But on cidtivating these j)lants and allowing- them to fertilize tliem- 

 .selv<'s it was found that the membei's of the 



Ratio- 



1 <ih class produce only (ih'>. 



,j \\ (I B class may pi-oduce eithei- all ^///s, 

 \'l or both (^///s and ah's. 



,f \l Ah fdass may produce eitliei- all ,l//s. 

 |2 "/• both J//s and <fh's. 



1 .1 // (dass may produce either all . I />'s, 

 ■2 or both .l^'\s and .l//s. 



2 or both AB'-i and r/B\, 

 4 o/' all four possitile classes again, namely. AB'-^. AVh^ 



tiB'^. and (ih'<. 



and the average number of memb<'rs of each clas> will apiMoach the 

 ratio 1:8: ?, : 1» as indicated attove. 



