Genetical Studies on Oenothera. V. 



185 



fortunately has not as yet seriously troubled my cultures. Emphasis 

 should be placed on this weakened vigor of the hybrids as compared 

 with the parents since hybrids of Oenothera in the Fi generally appear 

 to be fully as vigorous as their parents if not more so. 



Tig. 15. Inflorescence of liybiid, biennis >, muricata. Strongly matroclinous in the 

 "buds projecting far beyond the bracts. At the right is a leaf from near the base of 

 the main stem, patrodiuous in form but sliowing the influence of the biennis parent in 

 being obscurely toothed. Compare with Fig. 8, biennis, and Fig. 9, muricata, and contrast 

 with Fig. 14, muricata ,\ biennis. 



Great stress is laid by de Vries on the patroclinous tendencies 

 of the hybrids which with respect to certain characters are said so 

 nearly to duplicate the pollen parents as to justify the formulae 



Induktive Abstaniinungs- und Vererbungslehre. XII. l.-{ 



