Analysis of Heterogeneity in the Population 



275 



biotypfis 10 and 11 were separated by slight gaps, and in the females the extreme 

 end of biotype 8 was wanting. 



The second generation in this season showed the nearly complete development 

 of all of the lines in the population, no biotypic groups being absent, and none 

 separated from the mass of the population by discontinuities of any sort. This 



2289 Males. Total 4507. 2218 Females. 



Fio. 60. — Census of first annual generation at Chapultepec colony in 1907, 

 Ebowing great difference in tbe array presented by the two censuses in the pronotal 

 I>attern and also different from those present in the preceding censuses. 



14 42 31 



/ / 

 17 18 



46 



, \ \ 

 11 19 74 



3170 Males. 



12 31 41 

 Total 6782. 3612 Females. 



Fio. 61. — Census of second annual generation at Chapultepec colony in 1807. 

 The population was numerous and showed nearly the complete array possible for 

 the pattern in the population. Only a few of the extreme members in each of the 

 general lines are absent. 



condition in the population is not often attained at any location in this species, 

 and appears apparently only under the influence of optimum conditions in the 

 climatic complex. The findings in the two censuses of the season of 1907 

 are shown in figures 60 and 61, the conditions of the climatic complex in 

 climatic record 4. 



