\ tNTRODUCTION. 



mental study, l>ut for several years I was unable to do so. 

 rough pondence with Professor S. I. Bailey, who was at the 



tin tor of the Harvard Astronomical Observatory at Arequipa, 



oertained thai a wild species of cavy occurred in that locality. 



IY< :■ • r Bailey kindly captured some of the cavies and attempted 



eatedly to forward them to me, but without success. The steam- 

 ship roiiip.-inii-; n-fn>«'«l to accept them for transportation on the ground 

 that they might lead to detention or quarantining of their vessels, 

 .11 rodents were inspected of being carriers of bubonic plague. 

 1 yean of waiting and fruitless negotiation with every 

 chance traveler to Peru with whom I came in contact, I resolved to 



to Peru myself and get the desired specimens. Through a grant 

 made by the ( Sarnegie Institution of Washington I was enabled, in the 

 fall of 191 1. to carry this resolution into effect. 



The < larnegie Institution of Washington and the Bussey Institution 

 ha mther provided means for carrying out the breeding experi- 

 dm 9Ciibed in this paper. I wish to express my gratitude to both 



institutions and to thank the director and other officers of the Harvard 

 1 ege < Observatory for hospitality and generous assistance given me 

 at the Arequipa station. I am indebted also to Professor C. J. Brues 

 for kindly bringing me a stock of guinea-pigs obtained by him near 

 Lim l Peru, in 1912. 



