1 86 Heredity and Eugenics 



In 1908 individuals from this location were brought to 

 Chicago and carried as pedigreed cultures in the labora- 

 tory. They have shown a complete gametic purity as far 

 as could be determined and none have been detected which 

 were hybrid in character. In this colony, isolated in its 

 location, through some process or other in hybridization 

 or perhaps by selective factors, signaticollis has completely 

 subjected and eliminated undecimlineata. Inasmuch as 

 L. undecimlineata, when protected from crossing, lives 

 well at Cuernavaca, and the selective action is very low, 

 I am of the opinion that the swamping of undecimlineata 

 is due to some process of hybridization. This opinion is 

 fully justified by experiments conducted in cages which 

 eliminate selective factors. 



Another experiment was begun in 1905, when one 

 hundred individuals were taken from the standard colony 

 of L. signaticollis at Cuernavaca, and, with an equal num- 

 ber of L. undecimlineata, from El Hule, were planted upon 

 a vigorous growth of their food plants in a clearing made in 

 the Foot Hill Rain Forest, in the Paraiso district, not far 

 from Ojos de Agua, in the Canton of Zongolica. They were 

 observed to intercross freely, but there was a preponderance 

 of undecimlineata-like forms, with a few intermediates, 

 and only small numbers of the signaticollis type in the first 

 generation. The census made of the first hybrid generation 

 was as follows : 



Signaticollis Type Mid-Type Undecimlineata Type 



56 1,342 



A third generation was produced in late November, and 

 in that generation there were no signaticollis forms visible; 

 there were only a few of the hybrid intermediate type, and 



