352 



Quantitative Characters 



In a further study of corolla length, H. H. Smith introduced 

 some modifications of East's methods. He crossed Nicotiana 

 Langsdorffii with A^. Sanderae (Fig. 99) but used the geometric 

 mean between the length of the corolla tube and the length of 



Fig. 99. Measurements of corollas in Nicotiana Langsdorffii (left) and 

 N. Sanderae used by Smith in studies of corolla size. (Courtesy of Dr. H. 

 H. Smith in Genetics.) 



the maximum lobe for his measurements rather than just tube 

 length. Furthermore, he found, as did East, that the variation 

 of the original species was not comparable, for Sanderae, the 

 species with the larger flowers, showed much greater variability 

 than the other species. He adjusted this initial difference in 

 variability by plotting the various values not on an ordinary 

 arithmetical scale but on a logarithmic scale to the base 10. By 

 this technique, the picture of variability of the two species was 



