161 
15 : 1, considering the number of individuals involved in the 
cultures and the consistent results yielded by tliree different 
pedigrees involving reciprocal crosses. After the pedigrees were 
all arranged in the spring of 1910 for the testing of this hypoth- 
esis, Baur ^) suggested the same possible explanation in a 
review of one of my papers. 
The demonstration of two independent genes for the deter- 
mination of the same external character is to be found in the 
composition of the F3 families grown from self-fertilized individ- 
uals possessing the dominant character in question, — in this 
instance the biirsa-pastoris type of capsule. Letting the two sup- 
posed genes for the triangulär capsule be represented by the 
Symbols Cc and Dd, the gametic composition in Fg and the 
expectation in the F3 is indicated in the following table : 
Table IL 
Number of 
F2 plants in 16. 
1 
2 
2 
4 
1 
1 
2 
2 
1 
Gametic 
Composition 
in the 
CDCD 
CD Cd 
CDcD 
GDcd 
CdCd 
cDcD 
Cdcd 
cDcd 
cdcd 
Expected 
Results in Fq 
All hursa-pastoris. 
All bursa-pastoris. 
All bursa-pastoris. 
Bursa-pastoris and Eeegeri, 15 : 1, 
All bursa-pastoris. 
All bursa-pastoris. 
Bursa-pastoris and Heegeri^ 3:1. 
Bursa-pastoris and Heegeri^ 3:1. 
All Heegeri. 
The facts shown in this table may be summarized in the 
Statement that among fifteen families raised from Fg plants 
having the bursa-pastoris type of capsule, there will be on the 
average seven (1 CDCD 2 CDCd -[- 2 CDcD F 1 CdCd + 1 cDcD) 
which will breed true to that type, four (CDcd) will produce 
bursa-pastoris and Heegeri in the ratio 15 : 1 as in the Fo; and 
four (2 Cdcd -h 2 cDcd) will give these two types of capsules in 
the ratio 3:1. As in all other recessive types, the offspring of 
Fg plants having Heegeri capsules should produce no plants with 
bursa-pastoris capsules in the F.^. 
^) Zeitschrift für Induktive Abstainnumga- und Vcrerhiuigslelire 
''\ : 341—342, Je 1910. 
Veibandluiib'cii des uatuil. Vereines in Brünn. XLIX. 15:ind. H 
