ZUR GENETIK DES WEIZENS 85 
SUMMARY. 
In new strains of Triticum vulgare mutants of a peculiar genetic 
constitution occasionally appear. On account of their similarity to 
Triticum Spelta NıLsson-EHLE has termed these Speltoids. 
1. In 1914 in one of our pedigree-lines of fall wheat such a Spel- 
toid-heterozygote appeared, the offspring of which segregated ouly into 
plants of the type of the parental strain (Normal type) and Speltoid- 
heterozygotes. In order to study the modus of segregation and the gene- 
tic constitution of this hybrid in the seven succeeding generations about 
100,000 plants of its progeny has been grown and examined. In this 
progeny all types apparently different from the original heterozygote 
have been propagated in turn, and finally in 1919 a number of reci- 
procal crosses were made and the resulting F, was examined in 1921. 
2. The types in question each of which appears awned and awn- 
less (shown, all on the same scale, figs. 1—10) are: Normal type, 
Speltoid-homozygote and heterozygote, Typical and Short compactum- 
like heterozygotes and Square-head heterozygotes, further, Dwarf »com- 
mon wheat» and late »common wheat», both heterozygotes, and de- 
veloping about 4 weeks later than normal and a very late Perenne 
type which rarely produces spikes. Besides the differences in shape 
and size, marked differences in fertility and in modus of segregation 
are to be found even within the same type. 
3. Reciprocal crosses between Normal typé = NN and Speltoid 
heterozygote = SpN result for 2 NN X 4 SpN in plants of Normal 
type only, and for 2 SpN X 4 NN in plants of Normal type and Spel- 
toid heterozygotes only. These two types appear in nearly the same 
proportion as in the offspring of the heterozygous mother-type after 
self-fertilization. Therefore the production of the zygotes in this 
Speltoid-heterozygote by self-fertilization may be written: 
OWEN Sp) de (UN) = NN 2 SM, 
where n in the different lines of Speltoids has the values 1, 4, (5—7) 
or 8. The actual number of plants obtained is sometimes an uncer- 
tain expression of the ratio of segregation, because the Normal type 
being the most vigorous under adverse conditions appear too numerous. 
4. The factor for awns is linked to the Speltoid-complex so that 
the common awnless Speltoid-heterozygote is heterozygous in both, 
therefore awnless Speltoid-het. X awned Normal in the progeny gives 
but awned Spelt.-het., and vice-versa, awned het. X awnless Normal 
gives awnless Spelt.-het. in the progeny, accordingly awnless hetero- 
