284 



PRODUCTION OF RACES AND SPECIES IN LEPTINOTARSA. 



reared, the rubicunda giving in the two following generations typical rubi- 

 cunda without a trace of reversion, and the multitceniata no more rubi- 

 cunda. In the second generation of multitceniata reared at Chicago there was 

 found a single male mclanothorax, which was crossed with a normal female 

 multitceniata, giving a hybrid progeny of 14 males and 11 females interme- 

 diate between the two parents. These hybrids were again bred inter se, and 

 gave a Mendelian splitting of mclanothorax 6 males and 5 females, and 

 multitceniata (hybrids) 16 males and 18 females. In July, 1904, the series 

 was all killed excepting the melanothorax portion; these hibernated, and were 

 transferred to Mexico in March, 1905, where they have gone through two 

 more generations and are now hibernating. Thus far they have shown no 

 trace of reversion to the parental type. The history of this experiment is 

 given in text-figure 23. 



.GENEFUTI INS 



II 



III 



IV 



VI 



VII 



4 c? RUBICUNDA ) 



X All from Toluca. Mexico. 



10 9 MULTITCENIATA) 



HYBRIDS 

 20<?, 18? 



Reared at Mexico City aud carried to Chicago as pupae. 



RUBICUNDA 

 3<? ' J, 4? 

 RUBICUNDA 

 12,?, 10? 

 hibernated 



RUBICUNDA 

 20<?,| 26 9 



RUBICUNDA 

 14,?,] 16$ 



RUBICUNDA 

 Killed July, 



HYBRIDS 

 10 <?' lit? 



RUBICUNDA 

 2<J, 3 9 



hibernated 



I 



RUBICUNDA 

 6<?, I 10 9 



RUBICUNDA 

 *<?- '9 



HYBRIDS 



14 <y, 149 



biljeruateil 



r 



RUBICUNDA 



?<?, I 89 



RUBICUNDA 

 20,?,] 31$ 



RUBICUNDA 

 Killed .Inly, 



HYBRIDS 

 20,?, 18 9 

 Killi-d by fuugui 

 disease 



MULTITCENIATA 



5<?. i 39 



MULTITCENIATA 

 8<?, I 14$ 



MULTITCENIATA 

 20,?, I 419 



MULTITCENIATA 

 60,?, I 62$ 



MULTITCENIATA 

 Killed duly. 



Text-figure 24. 



During 1904 and 1905 several other sets of cultures with this species were 

 started, but they have not yet gone far enough to give results of certainty. 

 Unfinished as is the above experiment, it shows quite conclusively that there 

 develop suddenly from multitceniata, as there did from decemlineata, extreme 

 variations which breed true to type and behave in hybridization like species of 

 permanency. 



In August, 1903, I obtained at Toluca four males of the form rubicunda, 

 which were bred to ten females of multitceniata from the same place, and 

 from these were obtained a hybrid progeny intermediate between the two 

 parent forms. These hybrids were transferred to Chicago, where they were 

 again bred, and gave a Mendelian splitting into rubicunda, multitceniata, and 

 hybrids. These cultures were placed in a greenhouse, giving short hiberna- 

 tions and life cycles, with the results shown in text-figure 24. 



