UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



BOTANY 



Vol. 5, No. 6, pp. 223-231 Issued April 21, 1915 



QUANTITATIVE STUDIES OF INHERITANCE 

 IN NICOTIANA HYBRIDS. III. 



BY 

 THOMAS HAEPEE GOODSPEED 



Two previous reports have partially outlined the results obtained 

 in an effort to contribute to the knowledge of the inheritance of quan- 

 titative characters (Gooclspeed, 1912 and 1913). Cro.sses involving 

 three flower-size varieties of Nicotiana acuminata (Grah.) Hook, have 

 been investigated up to and including Fg. The first and second gener- 

 ations of these hybrids have already received consideration and it is 

 the purpose of the present paper to review the results previously 

 obtained and to take up briefly the nature of the F.;. 



The tables which follow are based upon over 13,000 measurements 

 of spread and length of corollas of flowers borne upon the three flower- 

 size varieties of N. acuminata and on the hybrids made between them. 

 The method of designation of parents and hybrids is the same as that 

 employed in a previous commimication (1912). The parents, one 

 F^ and one F^, population, and the F., were grown in the summer of 

 1913 under conditions as nearly as possible identical with those under 

 which the plants in this experiment were grown in 1912. 



The arrangement of the material in the form of freciuency distri- 

 butions and the consequent rearrangement of the data, and in some 

 cases the combination of two or more groups of hybrids of the same 

 pedigree, give to the figures an appearance somewhat difl'erent from 

 that presented in the earlier reports upon the same hybrids. The 

 frequency distributions for corolla spread of individual plants formed 

 the main basis for these earlier reports. In the present connection 

 such distributions are not of sufficient interest to warrant their inclu- 

 sion. The statistical constants for the tables which follow are not 

 given, as their significance is doubtful with such small populations as 

 were measured. 



