UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



BOTANY 



Vol. 5, No. 3, pp. 169-188 



Issued January 9, 1913 



QUANTITATIVE STUDIES OF 

 INHERITANCE IN NICOTIANA HYBRIDS. II. 



LIBRARY 

 NEW YORK 



BOTANICAL 

 QARDEIV. 



BY 



THOMAS HARPER GOODSPEED 



A preliminary report on the inheritance in F, of flower 

 size in hybrids produced from three varieties of Nicotiana 

 acuminata, and notes on certain sterile hybrids of N. Tahacum 

 varieties and N. sylvestris together with remarks on the present 

 status of the "unit character" conception in studies of heredity. 



In a previous report (Goodspeed, 1912) on the inheritance 

 of flower size in F^ hybrids of Nicotiana acuminata varieties 

 the following points were noted: (1) the parental varieties, 

 (varieties I, II and III) bore flowers during two seasons which 

 showed small fluctuation in corolla diameter and were definitely 

 set apart from one another in respect to this character, i.e., there 

 was no intergrading of one flower size variety into another; (2) 

 the parental varieties were distinguished from one another almost 

 solely in respect to this flower-size character; (3) the results of 

 the measurements of flower size in Fj showed that the fluctua- 

 tion in corolla diameter was practically twice as great and often 

 nearly three times as great in this generation as in the pure bred 

 parents grown in either of the two years during which their 

 flowers were measured, and (4) the measurements of the corolla 

 diameters of the flowers on the plants of each group of hybrids 

 gave an average diameter for each group which was practically 

 the same as the calculated average between the corolla diameters 

 of the corresponding two parents — i.e., each of the five average 



