[Proc. Roy. Soc. Victoria, 25 (N.S.), Pt. 1. 19121. 



Aht. ]\\. — Fitrther Ol»^ervati()n.s on, Oiickoceira gihsoni, the 

 Cause oj Worm-nod tdcii in CattU. 



Bv J. A. GILKUTH, \).\ .^c, .M H.C.V.S., ic, 



AND 



GEOlKilNA SWEET, D.8c. 



[Read litli Mairli, 19 L2]. 



Since the publication last year by the CommonAvealth of Aus- 

 tralia of our previous paper on Onchocerca f/ih-suni, several lines of 

 external evidence have become available, bearing on the original home 

 and host, the history of its occurrence and geographical distribution in 

 Australia, and the means of transmission of this parasite, etc.. so that 

 it seems desirable that the information should be made public, together 

 with a record of the results of series of exppiiincnts undertaken to 

 elucidate the life history. 



Historical. 



Evidence abtained by J.A.G. during the late expedition to the 

 Northern Territoiy most strongly corroborates previous statements by 

 others and ourselves that there is a^jradually iucreasiug extent of infec- 

 tion by Onchocerca gihsoiu\ the further north the cattle are reared; 

 that is, the further away from the ordinary ports of stock introduction 

 in the south and east. From the infomiation available at the time of 

 their writing (1910, p. 99) Doctors Cleland and Johnston considered 

 that the buffalo, import-ed into Australia fi'om Timor in 1826-8, was 

 the originating host, though, as shown by ourselves later (1911, pp. 

 2 and 34), it was at least highly likely that the Timor cattle imported 

 about 1824 and 1840 into the Port Essington settlement were the true 

 original hosts. However, an opportunity was available to J.A.G. of 

 examining a number of buffalo, the descendants of those introduced bv 

 Sir Gordon Bremmer in 1824 to Port Dimdas, and later to the main- 

 land. Tliese have spread from Port Essington southwards over the 

 swampy plains to very near Port Darwin. These buffalo, so far as 

 his ex|>erience goes, are all unatt'ected with Onchorerra. but all the 

 cattle depastured on the same country are more or less affected— 

 indeed, the greatest extent of infection yet seen was in a steer killed 

 at Port Darwin, the region of the brisket showing at least a hundred 

 nodule.s — so that, although experience is limited as regards the buft'alo. 



