UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



BOTANY 



Vol. 5, No. 15, pp. 439-450 



December 28, 1918 



NOTE ON THE EFFECTS OF ILLUMINATING 



GAS AND ITS CONSTITUENTS IN CAUSING 



ABSCISSION OF FLOWERS IN 



NICOTIAN A AND CITRUS 



BY 



T. H. GOODSPEED, J. M. McGEE and E. W. HODGSON 



I. INTEODUCTION 



In our laboratories considerable attention has recently been given 

 to the abscission problem. It came to the attention of one of us in con- 

 nection with an investigation of the partially sterile F^ hybrids between 

 Nicotiana Tabacum varieties (cf. Setchell, 1912) and N. sylvestris} 

 A preliminary study of the mode of abscission in these hybrids was 

 reported upon some time ago (Goodspeed and Kendall, 1916). As a 

 continuation of this work, abscission of flowers and fruits in the 

 Solanaceae and particularly in Nicotiana has recently been investigated 

 (Kendall, 1918) . Some studies have been made by one of us regarding 

 the relation of the environmental complex to the occurrence of abscission 

 and with reference to the mode of foliar abscission in Citrus (Hodgson, 

 1917, 1918). More recently attention has been called to the delicacy 

 of the balance between fertilization and floral abscission (Goodspeed 

 and Davidson, 1918). The present paper reports the results of experi- 

 ments upon the effects of illuminating gas and its pure constituents 

 in causing flower-fall, which represent a continuation of similar experi- 

 ments by Kendall (loc. cit.) on Nicotiana, together with a report on 

 experiments of the same type on the genus Citrus. The data sub- 

 mitted were considered preliminary at the time they were gathered. 

 Their interest and the fact that other more important matters have 

 put a stop indefinitely to any further accumulation of evidence make 

 it seem desirable to present them at this time. 



NEW \ou 

 QAKDKbi 



1 Cf. various papers in Univ. Calif. Publ. Bot., vol. 5. 



