CORRELATION OF Xantluiun AND LETTUCE SEED 309 



tions, although a stimulation of germination of implanted seed, when 

 the hosts are under short-day conditions, is not excluded. The nature of 

 the naturally accurring inhibitor is being investigated further. 



REFERENCES 



Bogorad, L., and W. J. Mcllrath. 1955. Indirect photoperiodic effects on lettuce 



seed germination. Plant Physiol., 30. 

 Bonner, J., and J. F. Thurlow. 1949. Inhibition of photoperiodic induction in 



Xanthiiim by applied auxin. Botan. Gciz-, 110, 613-24. 

 Evenari, M. 1957. The physiological action and biological importance of 



germination inhibitors. Symposia Soc. Exptl. Biol., 11, 21-43. 

 Geissman, T. A., P. Deuel, E. K. Bonde, and F. A. Addicott. 1954. Xanthinin: 



a plant growth-regulating compound from Xanthiiini pensylvanicum. I. /. Am. 



Chem. Soc, 76, 685-87". 

 Mcllrath, W. J., and L. Bogorad. 1954. Germination of lettuce seed implanted 



in Xanthium petioles. Abstracts 29th Annual Meetings, Am. Soc. Plant 



Physiol. 

 Mcllrath, W. J., and L. Bogorad. 1958. Photoperiodic floral induction of 



Xanthium and germination of lettuce seeds implanted in the petioles. Botan. 



Gaz., 119, 186-91. 



