306 The Mechanism of Evolution in Leptinotaesa 



of direct experimental analysis, in the laboratory and in nature, in at least a 

 few instances. These materials do show precisely the condition that Darwin 

 saw and considered in the variation phenomena in organisms and the condition 

 upon which much of the controversy concerning variations, their direction and 

 selection, have been based. In this an unfortunate cul-de-sac was produced by 

 the biometricians following Galton, which for many years completely befogged 

 the true situation as Darwin had seen it, and as it is now seen more clearly with 

 the aid of present methods of analysis. 



Throughout the series of observations there is constant delimited " variation," 

 no trace of heterogeneous undelimited conditions being present, nor is such to 

 be expected in a complex pattern-system of this sort, which is itself a product of 

 the interactions of simpler elements, " simplest characters," each the product of 

 an exact and demonstrable group of productive agents, so that the system dealt 

 with, as far as it is known, is physically exact in its constitution and action, and 

 delimited behavior is to be expected. Any other condition would be the basis for 

 most searching analysis to discover hitherto unrecognized agents and to deter- 

 mine their role and place in the system. 



This series of observations upon L. multitceniata Stal at the locations given 

 has been supplemented and tested by the minor test series made at different 

 points in the south Mexican region where this form is found. Some of these 

 locations have been mentioned in an earlier portion of this chapter. The results 

 at none of these were in any way different from those already described, and are 

 not given, purely on account of the space they would occupy. 



All that an examination of this sort can ever establish, even under the best of 

 conditions in nature, with natural species, is the determination of the results 

 of unknown antecedent series of causes. In the organic population a series of 

 events is passing, certain stable conditions which are capable of convenient 

 expression, in one form or another, and so in the medium another series is pass- 

 ing, some elements of which are measured, and the two are matched up as 

 seems most plausible on the basis of some hypothesis which may or may not 

 be true and applicable to the case in hand. The net result of an examination of 

 materials such as is presented in the preceding pages is solely a determination of 

 the range, extent, and direction of the diversity of the materials in nature, no 

 more, and at the same time some of the conspicuous associations of the factors 

 in the medium, and of their range and direction of diversity, and in its totality 

 of both series, there is accomplished only the preliminary rough blocking-out of 

 the problems that are necessary in any investigation. All further progress rests 

 in this, as in all other instances, on the analysis of the materials and conditions, 

 their relations, and the recombination of separated materials and elements by 

 synthesis under divergent conditions, and in these laborious, complicated analyt- 

 ical and synthetic operations alone lies the sole basis of further knowledge. 



One other point in this series of observations is of interest in this place, 

 namely, the effect produced by the treatment of the data by the methods of the 

 biometrician. If the series of data had been treated in this manner and only 

 the amount of the pigment present been considered, the result of the examina- 

 tion would have been a series of polygons of distribution, in which the phe- 

 nomena revealed by the analysis here employed would have been obliterated and 

 the resultant curves meaningless. One coujd find different polygons at different 



