500 MITZMAIN. 



followed by 60 Musca. The flies were used in much the same 

 manner as in the preceding experiments, the Musca feeding, after 

 contamination, from the wound made previously by healthy 

 Stomoxys on guinea pigs free from disease. 



All of these experiments were followed by negative results. 



There is demonstrated at least, that a wound caused by the 

 mouth prick of Stomoxys is not suitable for the entrance of 

 surra-infected material transported by the mouths and feet of 

 many house flies. A logical sequel to this series would be to 

 transfer the muscids, after they were supplied with infected blood 

 from Stomoxys-prohed wounds, to open sores and scratches found 

 on work animals. This work is under way at the present time. 



The probability of success by this method is indicated by 

 the experiments of the following writers: 



Musgrave and Clegg(23) transmitted surra to healthy animals through 

 the agency of house flies. 



Darling, (56) in the Panama Canal Zone, recently conveyed Tr. hippicum 

 to the mule by means of 18 house flies. 



THE CYCLICAL DEVELOPMENT OF TRYPANOSOMA EVANSI IN 

 STOMOXYS CALCITRANS. 



The literature is abundantly supplied with theories and con- 

 jectures in regard to the development of trypanosomes within 

 the body of the intermediate insect host. Aside from the 

 monumental work of Kleine, Bruce, and his collaborators, on the 

 development of trypanosomes in tsetse flies, we possess little 

 definite knowledge. In regard to Stomoxys as a definitive host, 

 the experiments that have been performed are far from satis- 

 factory, the most serious obstacle encountered being the inability 

 of various workers to keep this species of fly alive long enough 

 for complete investigation. The views of various investigators 

 are cited as follows : 



Austen (35) finds from the evidence submitted, no indication that trypa- 

 nosomes ingested by S. calcitrans pass through a developmental cycle and 

 they apparently disappear within forty-eight hours. 



Manson(40) notes that Stomoxys probably acts as the definitive host for 

 Tr. evansi and Tr. equinum. 



Schat(i4) is apparently convinced that Stomoxys serves as the definitive 

 host of Tr. evansi and that surra parasites propagate in the body of this fly. 



Ziemann(4i) thinks that Tr. vivax is transmitted by Stomoxys which acts 

 as a definitive host, the trypanosomes multiplying in its body. No experi- 

 mental evidence is cited. 



Leese(42) discusses cases of camel surra in India. He considers the me- 

 chanical theory of transmission perfectly adequate, and that a life cycle of 

 the development of the trypanosomes in the biting flies, Stomoxys and others, 

 is not tenable except by analogy. 



Gaiger(29) in speaking of Stomoxys and other flies mentions that no 



