200 I'KOCEEDINGS OP THE ROYAL SOCIETY OP QUEENSLAND. 



of the organisms work in a way that causes them to turn back 

 from concentrations of H and OH ions that Mould be detri- 

 mental. . . . The physiological effect of the acid, neutral, 

 and alkaline water upon the organism very probably has to do 

 with decrease or increase in the pe meability of the exposed 

 tissue cells (especially the gills in the case of fishes)." Alkalinity 

 increased and acidity at first caused a decrease in permeability, 

 but acidity if increased caused an increase in permeability, 

 so that, as' in the case of alkalinity, death was ultimately the 

 result. In regard to marine fishes the results of Shelf ord and 

 Powers indicated that the action of alkaline water produced a 

 normal permeability of the membranes, and it is likely that 

 an acid condition of the water would kill such fish by diminish- 

 ing the permeability (Wells, 1915, p. 245). 



As already stated, the appearance of the affected Queens- 

 land fish suggested suffocation, while the bulging of the eyes 

 noted by some observers strengthens the suggestion that the 

 water contained excess of carbon dioxide.^ 



(larbon monoxide is very poisonous to freshwater fish 

 (Shelford, 1917). Wells (1918, p. 562) ascertained that a con- 

 centration of from 75 to 100 cc. per litre COg would be required 

 to produce as deadly results as 1 cc. per litre CO, and that a 

 saturated solution of CO in water did not lose its toxic effects 

 even after two weeks' exposure to the air (p. 563). 



Another gas which is formed as a result of organic decom- 

 position, and may be added to water supplies as a result of 

 pollution by industrial waste, is sulphuretted hydrogen. 

 Shelford and Powers (1915 ; Shclford, 1918b) drew attention 

 to the extreme sensitiveness of fish to this gas, as they endea- 

 voured to avoid the presence of even a fraction of a cubic 

 centimetre per litre. Fish died in a few minutes in water 

 containing 7-6 cc. HgS per litre, and a combination of this gas 

 with CO2 was reported to be " exceedingly deadly." " Since 

 decomposition yields COg and consumes oxygen and is accom- 

 panied by the production of hydrogen sulphide which is also 

 accompanied by the consumption of oxygen, it is reasonable 

 to suppose that on a bottom from which vegetation is absent 

 and decomposition actively takes place, a fatal combination of 

 lack of oxygen and presence of hydrogen sulphide and probably 



^ For references to " pop-eye" of fishes see C. C. Farr, Rep. Austr. 

 Assoc. Adv. Sci. 13, 1911 (1912), p. 354 ; Ogilby and McCulloch, Mem.. 

 Q'land Museum, 5, 1916, p. 112. 



