30 GUrvJh (Did Sweet: Wortii-Nodules in Cattle. 



part of Northern Australia where vvonn-nodulos are prevalent there are 

 no fences, that the cattle on tlie average do not nearly ninnV)er 1 per 100 

 acres (often over large areas not 1 per 1000 acres), and the impossibilityof 

 copinp: effectually with tick fever in such countries, where the inter- 

 mediary host, the tick, is well known and cannot fly, the remoteness of 

 practical means of prevention is evident. 



In contradiction, it may be urged that certain biting insects have 

 been eliminated from certain distincts in the world ; but these have 

 been insects restricted to certain habitats such as watercourses, etc., 

 and we have previously shown that cattle from the driest areas are 

 often as seriously affected as cattle from wet districts, and that even 

 areas chiefly supplied by artesian water, are not by any means 

 immune. Nor so far as is yet determined by the evidence available 

 at freezing works, etc., is there any natural circumstance other than 

 latitude, which specially favours infection. 



This does not mean that we suggest that scientific investigation 

 should be discontinued, but that the stockowner and exporter can 

 hardly expect an extermination of the parasite. 



We desire to tbank Dr. W. Stapley, Mr. Norman MacDonald, and 

 Mr. H. R. Seddon. all of the Melbourne University Veterinaiy Institute, 

 for their assistance at various times in the above experiments. 



BIBLIOGRAPHY. 



rieland, J. B., and Johnston, T. H. — Report of Government Bureau of 

 Microbiology, Sydney, 1910, p. 91. 



Gilruth. J. A., and Sweet, G. — Onrhorerra j/ihsoni : the Cause of Worm- 

 nodules in Australian Cattle. Published by the Commonwealth 

 of Australia, 1911. 



Brumpt, E. — Precis de parasitologie, 1910. 



Lingard, A. — Obsei-vations on the Filarial lunbi-yos found in the 

 Equidae and Bovidae (I.), 1905. 



