rOle of stomoxys calcitrans. 479 



failure to infect was concluded only after the following examina- 

 tions. The temperatures of the horses and monkeys were regis- 

 tered twice daily. Microscopic examinations of the blood of 

 horses, monkeys, and guinea pigs were made each day. In these 

 examinations never less than 30 fields per blood film were 

 scanned. In the experiments with horses and monkeys an addi- 

 tional control was provided by guinea-pig inoculations. From 

 the horses 2 to 6 cubic centimeters of blood were drawn and 

 inoculated, from the monkeys 2 to 3 cubic centimeters. One 

 guinea pig was used for each animal tested. 



The animals were held in quarantine, both before and after 

 each experiment, in fly-screened sheds or cages; the horses in 

 fly-screened enclosures provided with a suitable double-door 

 vestibule, and the monkeys and guinea pigs in individual cages 

 which were made fly proof with double screens of close-meshed 

 gauze. 



Unless otherwise stated, in every experiment included in this 

 paper, an animal exposed to flies, whether through biting or 

 subcutaneous inoculation, was examined daily for thirty days 

 and afterward never less than twice weekly for ten days. 



EXPERIMENTS WITH HORSES IN A SCREENED STABLE. 



The experiments with the horses and Stomoxys were con- 

 ducted in a specially constructed fly-proof stable made to simu- 

 late natural conditions as nearly as possible. The enclosure 

 (Plate I) utilized in the present series was of the following 

 description. 



The walls and top were screened with brass wire of 16 to 

 18 meshes per inch. No roof was provided, and the animals 

 were protected from the sun by canvas screens stretched over- 

 head. A section was devoted to the growth of foliage provided 

 by acacia trees and hedge plants. A constant flow of water 

 was provided to aid in cooling the air within the enclosure. The 

 manure was not removed from these quarters, but was permit- 

 ted to accumulate in ant-proof wooden tubs at a little distance 

 behind the horses. The animals were watered from removable 

 iron containers within the mangers, filled by individual faucets. 

 The screened enclosure was divided into two parts by means 

 of a low partition formed of half-inch-mesh iron wire, ample 

 for the ready interchange of flies, and high enough barely to 

 prevent contact of the animals. A frame door closed the open- 

 ing from one stall to another, and a capacious fly-proof double- 

 doored vestibule served as a general entrance into the cage. 



