188 PROCEEDINGS OF THE ROVAL SOCIETY OF QUEENSLAND. 



6. Disease caused by parasites which may be — 



(a) Helminths, 

 (h) Protozoa — 



(i.) Myxosporidia, 



(ii.) Flagellata, Infusoria, 

 (c) Fungi, 

 {d) Bacteria. 



7. Two or more of the foregoing acting at the same 'ime. 



(1) DYNAMITE THEORY. 



It has been suggested that the use of dynamite as an 

 illegal means for obtaining fish might be an explana.tion of the 

 widespread mortaUty. 



The reports from the Severn and Mclntyre Rivers are 

 opposed to such an opinion. We think that the presence of 

 dead fish floating down the Brisbane River in 1918 was, at 

 least in part if not entirely, due to this cause. Specimens from 

 the locality submitted to us by Mr. H. A. Longman, Director of 

 the Queensland Museum, were found to have the s^\am-bladder 

 burst and the viscera disorganised, an effect such as one might 

 expect from the use of some high explosive. 



Mr. Ogilby of the Queensland Museum, in a letter to the 

 Brisbane " Sundaj^ Times " of 18th September 1918, referred 

 to the matter and stated definitely that boating parties in the 

 vicinity of Ipswich were in the habit of using dynamite, and 

 since they probably obtained not more than one in five of the 

 fish killed by the explosion the remainder would float down- 

 stream, such fish as perch {Scicena australis), sea mullet [Mugil 

 spp.), and catfish [Tandanus and Neosilurus) being recognised. 

 Mayer^ has recently referred to the effects of high explosives 

 on fish, especially on those possessing a swim-bladder. 



We believe that we may then rule out the Brisbane River 

 reports regarding the epidemic, but there is no justification 

 for attributing the widespread mortality elsewiiere to this 

 cause. 



(2) EFFECT OF CLIMATE. 



This should be treated under two headings — (a) the influ- 

 ence of dry weather and (6) the effect of temperature — but we 

 have not sufficient data to allow us to consider them separately. 



' A. G. Mayer, Yearbook, Carnegie Institution 1917, No. 16 pp 

 185-6; abstract in J.R.M.S., 1919 (3), p. 239. 



