BEITRAGE ZU EINER GENETISCHEN ANALYSE ZWEIER GODETIA-ARTEN 283 


G—g, G produces a red spot in the centre of the petal; Gg-plants have 
a smaller spot. | 
H—h, H enlarges the spot produced by G, but has alone no visible 
effect. 
I—i, I gives, probably only with B, rose-lilac colour. 
Linkage was shown to occur between B—b and E—e, E—e and 
G—g, C—c and F—f. Thus B—b, E—e and G—g are located in the 
same pair of chromosomes, while C—c and F—f both are located 
in another pair. As to B—b and E—e the gametic ratio was found 
to be about 6:1:1:6, the crossing-over percentage thus being about 
143. As to the other cases of linkage the ratio of gametes could not 
be determined. 
4) As to the size of the corolla it was shown that the aa-plants have 
a smaller corolla on the average than the plants with A. Probably 
other genes are also involved in producing differences in the size of 
the corolla. 
5) Single flowers are more or less completely dominant over 
double ones. 
6) Segregation as to leaf colour was shown to occur in several 
crosses, though classes could not be sharply distinguished. Dark co- 
lour dominates, though probably not completely, over light colour. 
At least two pairs of genes are involved. 
7) As to the shape of leaves genetical differences were shown 
to occur, and segregation was found to take place in F, from several 
length 
breadth 
was exactly determined, and a great number of leaves were measu- 
red. The’ genes for length and breadth were found to segregate more 
or less independently, and thus the segregation with regard to the 
shape of the leaf was produced. Probably only a few pairs of genes 
are involved. The genetical type of a plant can be determined only 
by measuring the leaves of its offspring as the modifications are very 
pronounced. 
8) The low, dense type of growth was shown to be recessive to the 
high, lax type, the segregation in F, being simple. The genes involved 
are named R—r. The gene R is probably inherited quite independently 
of the genes for flower colour, E and F. 
9) In amoena varietal crosses were made with regard to flower 
colour and doubleness of flowers. 
10) Two different homozygotically spotted types of amoena occur. 
crosses. , In order to express the shape the relative length = 
