No. 638] 



TYPES OF MUTATIOXS 



257 



recurrent twelve. Secondly, it should l)c ])(.ssi))lc l)y 

 breeding- tests to connect up mutants with as many 

 chromosome sets as there are known ^leiuloliaii factors, 

 or factor groups. This connection we seem to have estab- 

 lished between the mutant Poinsettia and the set of 

 chromosomes which carries the factors for purple pig- 

 mentation in flower and stem. 



TABLE ir 



T\PEs or Chromosomal Din i< \iioN e, ^mftk vnd^om^tu Fofmuve 

 FOR Plants Heterozygous for Factor Pair A axd a axd Ratios 



The set of \ chu>m..^.>iin ^ m Ju di >m mi 1 xhk II, 

 max bo calhd the PoiiiMttii m t, m th( pm].!. Mt V 



factor, hv coiisideml nulliplex with no dctniuMiit uvih>s, 

 or simplex, (hii)h'X oi- tri])lex with. ros]>('ct i\ 1. _\ (U- 3 

 dominant factors. 1 here ar(^ tluMTt oi-c two tvpfs ot 

 heteioz\gotes, and nndti ^1. I 1 linii^, (<iidl n-t'itM ij) 

 parently can be distmuuislicd irt.m caoli otiuT as wrll as 



