300 



The Mechanism op Evolution in Leptinotaesa 



distributed precipitation and other conditions optimum in their arrangement. 

 The findings in the population are shown in figures 103 and 104, 



The year of 1906 was a favorable year as measured by the range in the char- 

 acter presented in the population, as shown in figure 105, wherein no separate 



46 

 3034 Males, 



Total 5501. 



71 77 21 29 



2467 Females. 



Fio. 108. — Census of first annual generation at Puebla In 1905, showing entire 

 lack of Isolated groups and relatively wide range of population with respect to 

 conditions of pronotal pattern. 



T64> 

 61-^ 

 85- 

 S1-- 



'92- 

 iOT- 

 124- 

 101- 

 161- 

 146- 



12 19 21 



I I I 





toi^ 



61--^^ 

 6s -^[ 



121 — 



102 



171 



106-'- 



109- 



121- 



^-', 



40 



— A. 



•1.« 



|-|3^ 41 

 J*^„«4.|l22 



0^^?mz'i 



21, 



2463 Males 



/ \ \ \ r-^ 



19 



Total 5157. 2694 Females. 



Fig. 104. — Census of second annual generation at Puebla In 1905, showing 

 farther Increase In array of pattern and also a sharp Increase In the population la 

 regard to size. No Isolated groups. 



groups are present in the population; but the second generation of the year 

 showed isolated groups again in biotypes 5 and 10 in the males and in 10 and 12 

 in the females, all relatively small in numbers, as shown in figure 106. 



