VARIATION AND HEREDITY 135 



Mendel's simple theory explains the defi- 

 nite proportions ID A- 2P(TV) -4- 1TL nh- 

 served .when D anrl ^ ^TP. pms^r] It has 

 been tested in various ways, for instance, by 

 crossing D(R) with D or witk R. when 1 as 

 Demands, equal Timbers of 



W<\ P. or of (PR) and R. are ohtaine^. 

 In his exceedingly clear exposition of 

 Mendelism (1905), Professor R. C. Punnett, 

 himself a productive investigator, states the 

 characteristic Mendelian result thus : " Wfrgr- 

 ever there ...occuT's.a, pair oj ffiflfeyfint.jat.ing chfir- 

 of ^jn'oh cum T\ rlnminnnt tn the 

 exist I there a.re 



character ; 



t^ue ^o. tli f^f|nrn.in ant character and are there- 

 fore pure; and thirdly, 



wln'nK Tiin^ Inn nnllpH nrjp^^ ^pH whiVli cm 

 (nr 



fl.re_^ftpfl.ra.t.f f ) give both dominant 



forms i^ithp ^ Y ^rl prnport4on of 

 three of the former to one of the latter." 



Bringing the theoretical interpretation into 

 prominence that is, the theory of gametic 

 segregation, Professor Bateson, the leader of 

 the Mendelian school in Britain, says: "The 

 essential part of the discovery is the evidence 

 that the germ-cells or gametes produced by 

 cross-bred organisms may fa Aspect jgf^iven 



