CHAPTER IX. 

 ANALYSIS OF HETEROGENEITY IN THE POPULATION. 



It has been shown how the elements of the pattern found upon the pronotum — 

 simplest characters — ^behaTe with reference to different factors that are met in 

 the life of the individual. How some of these are related in the complex pat- 

 tern that is found on this portion of the body and the different aspects of some 

 of the problems of heterogeneity presented by this portion of the organism. 

 There remains the complex character as it is found in nature in the population, 

 the manner in which this system acts as it meets the ever-changing conditions of 

 its habitat, and the metathesis of simplest characters within the population 

 itself. A picture and an analysis of the conditions found will help materially to 

 gain a complete vista of the problems of heterogeneity in a complex character, 

 and help in some measure to aid in the understanding of the causes of this 

 heterogeneity, its limitation, and control within the population. 



For this survey of the conditions in the population the tropical forms have 

 afforded the finest material. The species L. multitcBniata Stal has been particu- 

 larly favorable for this analysis in nature and for the experimental studies^ both 

 in nature and in the laboratory. The fact of its complexity, the fortunate 

 diversity of its natural habitat, and the close proximity of habitats of widely 

 differing conditions have, in the aggregate, produced conditions of uncommon 

 excellence for the proper and successful pursuit of the problems. Ifaturally the 

 other species in the group have come in for their share of the same treatment, 

 but none of the other species has been given the time or attention that this one 

 has, and none has given the least indication of principles that were ia any man- 

 ner different from those found in the most exploited species. In the presenta- 

 tion of the rather extensive data, the condition found in each colony during the 

 time of observation, with brief comments upon the findings, will be first pre- 

 sented, and at the end a comparison and discussion of the results of the examina- 

 tion and census-taking, after which some of the experimental results wiU be 

 presented. 



IN LEPTINOTARSA MULTITj^NIATA. 

 THE CHAPULTEPEC COLONY. 



The character and general topography of this location have been already 

 described, as well as the methods of taking the observations, and the source of 

 the climatological data used to show the conditions that prevailed in the location 

 as nearly as possible during the time that the observations were being made. It 

 would have been far better if the records could have been made on the exact spot 

 where the organisms were living, but this was not possible, and the records 

 presented show fairly weU the general prevailing difference of conditions in this 

 and in the other colonies where observations were made. 



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