EFFECTS OF SAWDUST ON FISH LIFE 



53 



SESSIONAL PAPER No. 22a 



CONCLUSIONS. 



1. Strong sawdust solutions, such as occur at the bottom of an aquarium, poison 

 adult fish and fish fry, through the agency of compounds dissolved out of the wood 

 cells. 



2. The overlying water in such an aquarium does not at first kill fish. After 

 about a week it does kill, but solely through suffocation, the dissolved oxygen having 

 all been used up. 



3. Bacteria multiply enormously throughout all parts of such an aquarium, and 

 through oxidation change the poisonous extracts to harmless compounds. Mosquito 

 larvse live on the bacteria. No doubt, in natural pools, other aquatic insect larvae live 

 on bacteria also. 



4. Subsequent aeration and sedimentation of sawdust water purify it, so that fish 

 can live in it without injury. 



5. Since adult fish and black bass fry both refused to be driven into pine extracts 

 in the bottom of an aquarium after they had experienced its poisonous effects, we may 

 infer that fish would desert a river much polluted with freshly made sawdust, going 

 down stream and into tributaries to escape from the disagreeable influence of the saw- 

 dust extracts. 



6. Further observations and studies along sawdust polluted streams and rivers in 

 Canada are urgently needed before more definite conclusions can be reached. My own 

 observations on the Bonnechere are not sufficient to enable me to form any conclusion 

 that would be applicable to other rivers. In this connection I should like to quote 

 Professor Prince again : ^ Circumstances modify the effects of all forms of pollutions, 

 so that waste matters which would be deadly in one river will pass away and prove of 

 little harm in another, where the conditions are different.' 



ACKNOWLEDGMENTS. 



I must add finally, acknowledgment is due to Toronto University, the Public 

 Library, Toronto, and the Canadian Institute, for the privilege of consulting their 

 libraries in order to write the historical part of this report. 



I am under special obligations to my colleague. Prof. J. C. Connell, M.A., M.D., 

 for the large supply of minnows which he procured for me, and which were so in- 

 dispensable for the laboratory experiments. 



Dr. John Waddell and Mr. C. W. Dickson, M.A., both of the School of Mining, 

 Kingston, rendered valuable aid in determining the amount of solid matter in sawdust 

 water. 



The Ontario Fisheries Department greatly facilitated my task on the Bonne- 

 chere by instructing their overseers to assist me in every way possible. 



APPENDIX TO DR. KNIGHT'S REPORT ON SAWDUST AND FISH LIFE. 

 Bacteriological Examination of Sawdust Water in Shade and in Sunshine. 



Examination of sawdust water in aquarium made July 31, 1902. 



Two agar plates made. The first averaged 3,300 colonies of bacteria per cubic 

 centimetre. None of the colonies were spirilla which were present in large numbers 

 m direct microscopic examination of the water. The chief colonies were those of a 

 spore bearing bacillus, a variety evidently of B. Subtilis; also a few sarcinae, par- 



22a— 6 



