Analysis of Heterogeneity in the Population 313 



represented, and 8 was present in small numbers. In both sexes biotype 6a 

 stood apart from the population as a marked group, as did the extreme condi- 

 tions in 4 and a fairly strong group of 13. In the males some of the extreme 

 conditions of 9 were present as a poorly developed group. In the second census 

 the two sexes again showed the same conditions, in that the central mass had 

 changed in its shape by cutting off the extremes of biotype 5 as an isolated group 

 of some strength, and the increased development of 4 into a strong group. 

 Biotypes 6a and 13 were still represented in the population by isolated groups. 

 These conditions in the population are shown in figures 121 and 122. 



The last census made at this location was the first in 1909 and showed little 

 of interest. The body of the population showed the same condition that was 

 seen in the last census of the previous season, but the isolated groups had 

 dropped out, with the single exception of a small group of biotype 13 in the 

 females (fig. 123). 



In principle these arrays of the population through a series of generations and 

 seasons does not show anything different from that found in the data of L. mul- 

 titceniata. There are present in the population the same biotypes to some extent, 

 showing that in part at least the same complex system is being dealt with, but 

 in the population there appear other combinations that are not known in the 



Fig. 123. — First census at Tierra Blanca in 1909, showing condition of the 

 pronotal pattern. 



former series, as in biotypes 13, 14, and 15. In this series the same ranging 

 condition of the population over the possible pattern conditions is seen, but for 

 the location the range is limited to a relatively narrow series of changes, and the 

 isolated groups are uniformly conspicuously isolated from the mass of the popu- 

 lation. 



THE SAN MARCOS COLONY. 



I introduce the data of this location briefly, as a comparison of two locations 

 that are much alike in their topography, climate, and other conditions of life, 

 covering the same time and the same number of determinations as in the first 

 colony, but showing that the two are not at any time the same in population, 

 even though the same elements may be present (figs. 124 to 134). Com- 

 parison of the two series of determinations given will show the differences found 

 purely local in character, but of enough importance so that the differences 

 might well be productive of unlike results in different investigations, unless the 

 local differences in the constitution of the races are taken into consideration. 

 For purposes of some of the latter portions of this work it is necessary to have the 

 conditions present in these two locations for a basis of comparison, as they are 

 the base locations for most of the materials that have entered into some of the 

 more important experiments in nature and in the laboratory. 

 21 



