Analysis of Heteeogeneitt in the Population 



297 



In the following season (1909), none of the introduced conditions were found 

 in the population in either of the censuses, the only trace being a single de- 

 formed weak female of biotype 13 in the first generation of the season, which 

 did not reappear in the second annual population. In the second generation a 

 small group of isolated males of biotype 6 were present, but were too few in pro- 

 portion to the total population to have any meaning (figs. 98, 99). 



Evidently something that has happened in the location and in the population 

 has obliterated the introduced stock in a relatively short time and held the state 

 of the population at a fairly constant average, in spite of the disturbances of 



541 Males. Total 1082. 541 Females. 



FiQ. 98. — Census of first annual generation at Chalcicomula In 1909, showing 

 massing of population in or close to biotypes 7 and 8, with only a few present 

 in the divergent group of biotype 11 in the females. 



12- 



25 ^ iM 78 



14 



389 Males. Total 846. 457 Females. 



Fig. 99. — Census of second annual generation at Chalcicomula In 1909, showing 

 massing of population in still more restricted zones around biotype 7, practically 

 eliminating all biotypes introduced from outside. 



the introduced strains carrying divergent factorial conditions that might easily 

 disrupt the population of this restricted area. The experiment is suggestive, 

 but from it one can not decide whether the resulting rapid incorporation of the 

 introduced stock and its characters is due to the dominant character of the 

 native material, to the conditions of the environment, which either eliminated 

 the introduced forms, or has made them recessive in the population, with final 

 eradication from the constitution of the race at that localized area. 



At the end of this season I introduced from the Puebla colony a large army of 

 immigrants, 1,845 females and 2,134 females, a horde outnumbering the native 

 population several times. These hibernated with the natives, and apparently 

 20 



