127 



in the verminous nodules is an aberrant larva of H. muscae. 



In his earlier communication he says that in a few post- 

 mortem examinations made at Zambi no specimens of H. 

 megastoma were found. His conclusion was that H. megastoma 

 was either absent or very rare at Zambi. In his experiment 

 he, therefore, deposited larvae of Musca domestical on a freshly 

 voided mass of dung from a horse "known to be infected with 

 H. muscae." When the adult flies hatched out they were found 

 to be infected with larvae in a proportion of 70 per cent. 

 Larvae isolated from some of these flies and transferred on to 

 the hair or shaved skin of a horse were found to die off rapidly 

 and show no tendency to pierce the skin. When deposited on 

 wounded surfaces covered with serous fluid they executed 

 movements, and showed a marked tendency to become lodged 

 in small crevices. He also deposited larvae in the inner 

 canthus of the right eye of a horse which was kept isolated 

 within an enclosure surrounded by fine mosquito netting. The 

 animal subsequently became affected with conjunctivitis, and 

 verminous nodules developed on the membrana nictitans. The 

 left eye, which served as a control, showed no change. 



A further experiment was conducted in which two wounds 

 were made in the skin of a horse; one wound was protected 

 against flies and the other was left uncovered. The animal 

 was placed in a stable in which 20 per cent, of the flies were 

 infested with Habronema larvae. The unprotected wound 

 became the seat of intense irritation, which caused the horse 

 to bite itself. The wound became transformed into a char- 

 acteristic "summer sore." 



Discussion. 



There can be no doubt that the etiology of the tumours 

 found in Southern Australia and of those found elsewhere, and 

 usually called "summer sores," is the same. The larvae found 

 in "summer sores" appear to be identical with those found in 

 Southern Australia. Fayet and Moreau, Descazeaux and van 

 Saceghem have all described the presence of longitudinal ridges 

 in the cuticle, which also* characterizes the larvae found here. 

 Unfortunately the descriptions of the larvae have been very 

 inaccurate, and in many cases they have been regarded as 

 adult forms. It was not until recently that the etiology of the 

 condition was established by Railliet in his interpretation of 

 the work of Descazeaux. 



Although there are certain variations in the characters 

 of the lesions, for the most part they are fairly constant. 

 Those lesions in whfch embryos have been found do not appear 

 to resemble a typical "summer sore" very closely. Railliet 



