56 



THE BOTANICAL MAGAZINE. 



[Vol. XXXVI. No. 426. 



The actual numbers nearly 

 coincide with the theoretical 

 numbers, when the F x plants' 

 gametic ratio is calculated as 

 6.4 : 1 : 1 : 6.4. Thus, the cross- 

 over percentage between v and 

 d is 13.51 o/ 0m The heart- 

 shaped leaf (h) is a simple 

 Mendelian recessive to the nor- 

 mal (three lobed leaf). I 

 obtained the F x plants having 

 genotype YvHh from the cross 

 VVHH x vvhh. From these F t 

 plants were produced the 

 offspring shown in the follow- 

 ing table. 



HV 

 F 2 experim. numbers 736 



Theoretical numbers 750.638 



Boiled and normal leaf. 



Hv 



hV 



hv 



Total 



214 



221 



112 



1283 



211.607 



211.607 



109.148 



1283 



When the gametic ratio of the Fi plants is calculated as 1.4:1:1:1.4 

 the theoretical number almost agree with the experimental numbers. 

 Thus I would recognize that this ie also a case of coupling between 

 the factors h and v, although its intensity is low. Hence, the cross- 

 over is 4el.67% . Recognizing the linkage between v and d, and 

 between h and v, respectively, a linkage should be found between h 

 and d. I have also proved that there is a linkage between the factors 

 h and d by the experimental crosses DDHH x ddhh, the results of 

 of the segregation being as in the following table : 





DH 



Dh 



dH 



dh 



Total 



F 2 experim. numbers 



537 



182 



177 



82 



1028 



Theoretical numbers 



596.303 



175.096 



175.096 



82.505 



1028 



When the gametic ratio of F t plants is calculated as 1.3:1:1:1.3 

 the theoretical numbers almost agree with the experimental numbers. 

 Thus, the cross-over percentage between h and d is 43.48^. 



The three factors d,h, and v constituting a linkage group, may 

 be considered to be arranged on the same chromosome. The distance 

 between v locus and d locus is 13.51, that between v and h 41.69, 

 and between d and h 43.48. If the order of loci on the chromosome 

 is as h, v, d, or h, d, v, the distance between h and d should be 



