UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



BOTANY 



Vol. 5, No. 9, pp. 273-292, plate 36 October 4, 1916 



ON THE PARTIAL STERILITY OF NICOTIAN A 



HYBRIDS MADE WITH N. SYLVESTRIS 



AS A PARENT. II 



BY 

 T. H. GOODSPEED and A. H. AYEES 



CONTENTS 



PAGE 

 Introduction 273 



Response of the Hybrids and Parental Pollen to Natural and Artificial 



Germinating Fluids 276 



Experiments upon the Eelation of Nutrition to Sterility and Flower-fall 281 



Summary of Eesults 288 



I. Introduction 



In 1913 one of us reported that the several F^ hybrids made in the 

 University of California Botanical Garden between five Nicotiana 

 Tabacum varieties and N. sylvestris agreed with one another in pro- 

 ducing a small quantity of open-pollinated seed, while no seed was 

 produced on the same plants under bag (Goodspeed, 1913). These 

 interspecific hybrids had previously been considered to be completely 

 sterile with the exception of such evidence as is given by the experi- 

 ments of Bellair (1913), who grew an F, from seed of apparently 

 unprotected flowers produced on F, hybrids of probably much the 

 same parentage as those with which we have been concerned. Since 

 the publication of the original description of the partially sterile nature 

 of these F, hybrids further investigations, consisting primarily of 

 efforts to determine and modify the nature and causes of this sterility, 

 have been continuously in progress. The present paper is the first 

 report of tlie results of these investigations. 



The general problem as it presents itself to us seems a complicated 

 one, and tlius it 7n;iy be desiral)le to state it in the most general terms 



