284 



PRODUCTION OF RACES AND SPECIES IN LEPTINOTARSA. 



reared, the nihicimda giving in the two following generations typical ruhi- 

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

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

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

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

 diate between the two parents. These hybrids w^ere again bred inter se, and 

 gave a Mendelian splitting of melanothorax 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. 



4^ RUBICUNDA ) 



X Al 

 10 9 MULTIT/ENIATA) 



from Tolaca, Mexico. 





HYBRIDS 

 20 <^, 18 9 

 Hibernated 



Beared at Mexico City and carried to Chicago as pupae. 



RUBICUNDA 

 3<?, 1 49 



RUBICUNDA 



12^, 109 



hibernated 



1 



RUBICUNDA <^ 

 20<J,| 26 9 



'hybrids 



10^,j149^^ 







MULTIT/ENIATA 

 5^, j 39 



RUBICUNDA 

 2$, 39 

 hibernated 



i 



RUBICUNDA 

 %$, 1 109 



HYBRIDS 

 14^, 149 

 hibernated 



r — - 



RUBICUNDA 



n, 1 89 



HYBRIDS 

 20^, 18 9 

 Killed by fungus 



MULTIT/ENIATA 

 8^, 149 



MULTIT/ENIATA 

 20^,1 419 



RUBICUNDA 

 14^,| 169 



RUBICUNDA 



Killed July, 



1901. 



RUBICUNDA 

 4^, 19 



RUBICUNDA 

 20 $, 31 9 



disease 



MULTIT/ENIATA 

 60^, 1 629 





RUBICUNDA 

 Killed July, 



1901. 





MULTIT/ENIATA 

 Killed July, 

 l&Oi. 





Text-figure 24. 







II 

 III 



IV 



V 



VI 



VII 



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 shov/s 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 riihicunda, 

 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 h3'brids were transferred to Chicago, where they were 

 again bred, and gave a Alendelian splitting into ruhicunda, 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. 



