CREIGHTON AND MCCLINTOCK 



159 



coming from colorless, waxy (c-wx) 

 kernels should be knobless. Although 

 the data are few they are convincing. 

 It is obvious that there is a fairly close 

 association between the knob and C 



To obtain a correlation between cy- 

 tological and genetic crossing-over it 

 is necessary to have a plant hetero- 

 morphic for the knob, the genes c and 

 zvx and the interchange. Plant 338 



(17) possessed in one chromosome the 

 knob, the genes C and tvx and the in- 

 terchanged piece of chromosome 8. 

 The other chromosome was normal, 

 knobless and contained the genes c and 

 Wx. This plant was crossed to an in- 

 dividual possessing two normal, knob- 

 less chromosomes with the genes c-Wx 

 and c-wx, respectively. This cross is 

 diagrammed as follows: 



Wif 



Vx 



The results of the cross are given in ing a knob, whereas all the colorless 

 table 3. In this case all the colored kernels gave rise to individuals show- 

 kernels gave rise to individuals possess- ing no knob. 



Table 3 



Knob-C-ii).Y-interchanged Knobless-t-TFx-normal 



Knobless-c-lF.r-normal 



Knobless-c-ti'x-normal 



