142 C. HAMMARLUND 
dem normalen nicht genotypisch identisch ist. Die rotblättrige Form 
»rubra» habe ich mit »grün» pyramidisch und grün rosettenförmig 
gekreuzt. Fı ergab das Resultat, dass rotblättrig über grünblättrig 
dominierte. In Fa verhält sich diese Kreuzung eigentümlich, aber 
darauf werde ich später, wenn die Untersuchungen beendigt sind, 
zurückkommen. 
SUMMARY. 
Two crosses with different types of spikes have been analyzed. 
I. Branched X normal (nnBB X NNBB) gave a monohybrid 
segregation in F2, branched being recessive. 
The modification of the branched type was the most characteristic 
in this cross. The modification sometimes went so far that geno- 
typically segregating families were not to be distinguished phaenotypi- 
cally from the normally spiked type. 
II. Pyramid X normal (NNbbcc X NNBBCC) gave a dihybrid 
segregation in F,: 12 normals:3 rosettes: 1 pyramid, showing that 
normal dominates the rosettes and the pyramids, and the rosettes the 
pyramids. It also shows that B is epistatic to C. 
N is supposed to be a factor prohibiting the branching of the 
spike. 
B is a factor which prohibits the bracts from developing into leaves. 
C is a factor which, when B is absent, shortens the spindle of the 
spike and produces rosetted spikes. 
It is to be noted that the rosette-spiked type is less vital during 
unfavourable weather conditions. 
ZITIERTE LITERATUR. 
_ 
JOHANNSEN, W. Elemente der exakten .Erblichkeitslehre, 2 Aufl. Jena 1913. 
MININ, A. Zur Frage über das Entstehen der Pflanzen, welche von der Nor- 
malform abweichen, Moskau 1910 (russisch). 
3. DE Vries, HUGO. Die Mutationstheorie, Bd. I u. II. Leipzig 1901—03. 
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