Analysis of Heterogeneity in the Population 287 



in the array, which might have been due to the small number in the original 

 collection in this generation. The findings in this generation are given in 

 figure 79. 



In the season of 1904 two censuses were made, comparable in time with those 

 at the two other colonies in the valley of Mexico. The first one for the first 

 generation did not exhibit any considerable change from the condition presented 

 in the population of the preceding year, with the exception of the better develop- 



9 — 'liE\,., 



12 .4S^. ^^r... 14 --iaifc ■ .is^^ 



21 jg^ ^:^^ 22 20—^---^^ -^:i^ 29 



39-^— -^ ^ 46 44---^--^^ %^" ^ 35 



-^WSt^S* v*t 59 ^^^,_M'T-r- 74 



I I ^ '^ ^eV^ 39 / y — v'*^%i" ^^ 



III \ ^ 46 / /^ '^¥^ 33 



/ / / \ ^ / / \ \ 



7 11 21 ft 6 14 2 9 



350 Males. Total 704. 354 Females. 



Fig. 79. — Census of second annual generation at Tlalnepantla In 1903, showing 

 conditions of pronotal pattern. 



' ^ #- 16 i7-:-«^'„ 



46- -m W 38 3^ —m ■ m- 31 



■29 ^ ^ 51 33 — - -^ m~ 77 



^ -^S* 77 "^^''^L *^— . 8& 



/ ^ -if* ~T 46 / /'^ AS|^----19 



I \ / / ^ 



9 7 8 5 1 



384 Males. Total 747. 363 Females. 



Fig. 80. — Census of first annual generation at Tlalnepantla In 1904, showing 

 condition of the pronotal pattern at that time. 



11 ^ 14-, ;||^ 



29 5^ 9 m 



31 «t .1^ 4s 29 m m-—M 



44—- ^ ^i 52 46 ^^ m 29 



.^m m 77 ^*fe: — ^ 



/-/^3|* ^^^ 38. /^<^^ 46 



/ / \ ^ 29 



7 14 5 5 22 



383 Males. Total 718. 335 Females. 



Fig. 81. — Census of second annual generation at Tlalnepantla in 1904, showing 

 the presence of a single isolated group of females, the rest of the population 

 fairly uniform in its distribution. 



ment of biotype 4 and a few biotype 3 individuals in the female population. On 

 the whole, the population was massed on or near to biotype 7, the pivotal one in 

 the series. The second generation did not show anything different from the 

 first — only a somewhat more restricted range in the extremes of the population. 

 The conditions as found are recorded in figures 80 and 81. In amount and dis- 



