EXPERIMENTS WITH CEHT'AiN DIFTEKA AS 



mssiBLR TKANSMrri'KKS 01' i;0VfXK 



OXCHOCRKCIASIS. 



By Piofe.>.sor T. Harvey Johnston, M.A.,D.8c., ; and M. J. 

 Bancroft, B.Sc, Walter and Eliza Hall Fellow in. 

 Economic Biolog}', University, Brisbane. 



(With 16 Text-figures) 



{Read before the Royal Society of Queensland, 2Sth Axiril, 1920). 



Onchocerca gibsoni Cleland and Johnston. 



A survey of the early work on bovine Onchocerciasis 

 was published by one of us in 1911, while later work was 

 again summarised in 1916 (Johnston 1911, 1916). 



The probable origin of the parasite and its geographical 

 distribution have been dealt with by Cleland and Johnston 

 (1910) and by Gihnith and Sweet (1911, 1915). The anatomy 

 of the worm, pathological effects and seat of infection have 

 been fully treated by the above mentioned authors and 

 also by Leiper and Breinl. 



Nothing is yet definitelj' known regarding its life 

 history. All efforts to find the embryos in the blood 

 circulation have been unsuccessful, though Cleland showed' 

 that they may occur in the subcutaneous tissue. In post 

 mortem examinations of infected cattle, they have been 

 found in smears from the reflected skin or subcutaneous 

 tissue of \'arious parts of the brisket, legs and neck. 

 Cleland also found living embryos in thickened areas under 

 the! skin of cattle. Breinl showed that embryos can pene- 

 trate the skin of the beast, though he himself regarded the 

 result as perhaps pathological. Nicoll, though unable to 

 confirm Breinl's work demonstrated that the larvse were 

 capable of migrating through the thick capsule of the nodule 

 in considerable numbers. 



