532 THE AMERICAN NATURALIST [Vol. LIII 



habitats and stations, in shade and sun, and in relatively 

 wet and relatively dry soils. They show in every case a 

 small variation within each plant, but a great variation 

 between different plants, the averages ranging from 29.3 

 to 52.1. It happens that the plant with the largest num- 

 ber of heads also presents the highest flower-number, 

 but in general there is no correlation between them, and 



TABLE Tir 



Vakiatiox in Flowek-numbek on Different Plants 



the third highest avera^uc is presented by \\w plant with 

 the smallest number of heads. 



The last four plants, numbers 19 -22, were collected 

 fi'om the same station and grew under similar environ- 

 mental conditions in the usual (and for the region prob- 

 <'il)Iy also the optimum) habitat of the species. They also 

 |)i"esent very similar averages in their flower-number. 

 Others of the same station were also examined and 

 demonstrated tliaf e^^eiitinlly the same averages were 

 repeated throiiuhoul the lii'-Mijt. 



From an examinat ii)ii ot this table and from additional 



