284 HANS RASMUSON 

One of them has a red spot at the base of the petals (»Basalfleck», 
type II), -the other has a more lilac red spot across the middle part 
of the petals (»Querfleck», type I). The heterozygotes between these 
two types possess both spots (type III) and segregate in F, in the 
ratio 1:2:1. As in the F,-generation from crosses between these 
types and unspotted Whitneyi-forms the two types segregate in the 
ratio 3:1 and as, further, only the types I and II were obtained in a 
cross between type III and an unspotted form, a case of multiple 
allelomorphism possibly is present here, My numbers, however, 
are rather small and the case is perhaps only one of high linkage. 
Two pairs of genes (K, producing the »Querfleck», L, producing the - 
»Basalfleck» ) are preliminary assumed. . 
A sectoral chimaera was obtained in one of my F,-generations, 
which had flowers of both the type III and the type II. This is 
probably a case of mutation. Pi 
11) There are two double-flowering varieties in amoena. One has 
almost single or only a few double flowers with seldom more than 
5—6 petals, the other has all or nearly all flowers double and mostly 
with a great number of petals. The pronounced double race is more 
or less dominant over the less double one. The ratio 3:1 is obtained 
in F;, though the classes are not distinct. The pair of genes involved 
is named U—u. The plants of the colour type II are always more 
pronounced double than those of the type III, and these are more 
double than those of the type I. Thus the gene L has an augmenting 
effect, or the gene K an attenuating effect, or they are closely linked 
with genes of such effects. On the plants of the slightly double race 
this effect is much smaller than on the plants of the other race, and 
thus the 3:1 ratio in F, is obtained. 
12) No Oenothera-like phenomena did occur in the varietal 
crosses. Only one case of a probable mutation (the chimaera) was 
found. 
13) In the crosses between Whitneyi and amoena all the ‘F;- 
hybrids were almost completely sterile both as to the pollen and as 
to the ovules, and therefore only very small numbers were ob- 
tained in F;. 
14) A segregation in F, did occur as to flower colour, doubleness 
of flowers, heigth of the plant, length of the internodes in the flowering 
part, and probably as to colour and shape of leaves. The two latter 
characters, especially the shape of leaves, are rather modifiable and 
