1 86 Ucrcdiiy and Eugenics 



In 1 90S individuals from this location were brought to 

 Chicago and carried as pedigreed cultures in the labora- 

 tor}'. They have sho\\'n 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 perha])s by selective factors, sigiiaticoUis has completely 

 subjected and eliminated undccinilincata. Inasmuch as 

 L. iijidcci)iiliiicata, when protected from crossing, lives 

 well at Cuernavaca, and the selective action is \'erv low, 

 I am of the opinion that the swamping of iDidcciniUiieata 

 is due to some process of hybridizalioii. 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 colonv 

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

 ber of L. uiidcciniUncata, from YA 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 (3jos de Agua, in the Canton of Zongolica. They were 

 observed to intercross freely, but there was a preponderance 

 of iiiidccimliiicafa-like forms, with a few intermediates, 

 and only small numbers of the siguaticollis type in the first 

 generation. The census made of the first hybrid generation 

 was as follows: 



Sii^mlicoU!^ Type Mid-Type Umiecimlin^ata Type 



o 56 1,342 



A third generation was produced in late November, and 

 in that generation there were no siguaticollis forms visible; 

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



