Analysis of Heterogeneity in the Population 



317 



Comparison of the two locations is shovm in figure 135, in which the outlines 

 of the populations are sho^vn as in figure 111 for L. muUitceniata for its different 

 locations. L. undecimlineata, while conspicuously less widely ranging in its 

 pattern, an " invariable " species, shows the same set of conditions present and 

 acting in the same system, as was seen in the first species, and could the investi- 

 gation of this species have been followed advantageously for a widely separated 

 set of places most interesting arrays quite different in their composition would 

 have been seen. As it is, in the consideration of the geographic aspects of this 

 complex pattern some indication of the diversity present in many localities is 

 obtained. These, while not presenting the entire series of ever-changing differ- 

 ences that are found in the population, reveal that over the range of the species, 

 as a whole, different locations in space constantly show differences in the array 

 of the pattern presented — instances of determinate variation. 



1904 1905 1906 1907 1908 1909 



Fig. 135. — Diagram representing the conditions found in the two populations 

 o( L. undecimlineata in the colonies of San Marcos and Tierra Blanca, during 

 the period of observation. Although the colonies are essentially alike, as far as 

 populations are concerned, there appear to be minor constant differences present 

 In both. 



One other instance of the series, namely, L. decemlineata at Chicago, for a 

 series of years, will complete the presentation of this portion of the data. 



IN LEPTINOTARSA DECEMLINEATA. 



In the populations of this species I had examined in Massachusetts, Long 

 Island, and Ohio, I had found that there were present in this character associ- 

 ated conditions that could be grouped into assemblages that were capable of 

 isolation into true-breeding groups, as far as the analysis had then been carried. 

 Further analysis of this condition at Chicago between 1902 and 1907 showed 

 that in the population there were five groups that coujd be isolated and that 

 would breed true in mass cultures without further selection, once they had been 

 purified. This species is poor in elements of the pattern, none of the extra 

 areas being present, and only the main elements are represented. So, also, the 

 species is poor in possible combinations and is quite distinctive and specific in 

 this respect. 



THE CHICAGO COLONY. 



There are present at Chicago five biotypes, 7, 4, 8, 9, and 13. In some other 

 locations in the range of this species there are indications of the presence in the 



