lg THE BOTANICAL MAGAZINE. t Vo1 - xxxiv. No. 399. 



The results almost agree with the theoretical numbers calculated 

 from the ratio of monohybrid. 



The rolled leaves also reappear in the F 2 generation, as is shown 

 in the following table :— 



' Observed Expected 





Flat 



Rolled 



Total 



Flat 



Rolled 



1). 



S.E. 



5x9A— a 



13 



3 



16 



12.00 



4.00 



±1.00 



±1.73 



„ -b 



187 



67 



254 



190.50 



63.50 



±3.50 



±6.91 



» ~ c 



9 



5 



14 



10.50 



3.50 



±1.50 



±1.61 



», ~d 



30 



14 



44 



33.00 



11.00 



±3.00 



±2.87 



5xAX— a 



26 



5 



31 



23.25 



7.75 



±2.75 



±2.41 



» ~b 



12 



3 



15 



11.25 



3.75 



±0.75 



±1.67 



Totals 277 97 374 280.50 93.50 ±3.50 ±8.37 



Thus the rolled leaf acts as a recessive to the normal condition 

 and segregates following the simple Mendelian ratio. 



Considering these two characters together the^four different kinds 

 of plants are expected to be produced in F 2 according to a 9:3:3:1 

 ratio, if the combination of the factors responsible for these characters 

 follows the ordinary dihybrid scheme. The results obtained, however, 

 were different from the expectation as will be seen in the following : — 





Observed 







Expected 



Homoge 

 colorei 



neously- 

 1 



Rolled 



Vari 



Flat 



iegated 



Homogei 

 colored 



Flat 



leously- Variegated 



Flat 



Rolled 



Rolled Flat Rolled 



5x9A—a 12 







1 



3 



11.06 



0.93 0.93 3.06 



„ — b 168 



19 



18 



49 



175.51 



14.73 14.73 48.51 



n -C 9 



1 



2 



2 



9.67 



0.81 0.81 2.67 



n -d 29 



5 



2 



8 



30.40 



2.55 2.55 8.40 



5xAX— a 23 







3 



5 



21.42 



1.80 1.80 5.92 



„ -b 11 



1 



1 



2 



10.37 



0.87 0.87 2.87 



Totals 252 



26 



27 



69 



258.43 



21.69 21.69 70.43 



The data given above may be explained by assuming the presence 

 of a coupling between these two characters. If we assume the fre- 

 quent distribution of gametes as 7:1:1:7 according to Bateson 

 and Punnett's scheme, the expected numbers thus calculated cover 

 pretty well the results as have been represented in the above table. 



P.S. After this paper has been written a similar case was reported by Y. Imai 

 in Japanese (" Genetic studies in Morning Glories. I." Botanical Magazine Nqs 

 394 and 395, Vol. XXXIII. 1919.) 



