46 MARINE AND FISHERIES 



6-7 EDWARD VII., A. 1907 



Hemlock Sawdust. 



Weight 

 of 



Sawdust. 



Volume 

 Water c. c. 



lime 

 Soaking. 



Time 

 at which minnow 

 was immersed. 



"Results. 



2 grams. 



300 



10.15 a.m. 



2.30 p.m. July 



... 



July 26, 9.30 a.m. Dead. 







of 23rd. 



23. 





400 











500 







July 30, 9 a.m. Released. 





600 









700 











800 







July 26, 9 . 30 a . m. Found dead. 





900 







Lived 45 minutes. 





1000 







July 26, 11a.m. Dying. 





1200 







28, 3 00, Dead. 





1500 







Lived 1 hour and 45 minutes. 





1700 







July 26, 9.30 a.m. Dead. 



Spruce Sawdust. 



2 grams. 



300 



10. .30 a.m. 



2.40 p.m. .July 



Lived 3 hours and 50 minutes. 





of 23rd; 



23 . 







400 







July 24, 9.30 a.m. Found dead. 





500 





II 





600 





II 



" 26, !! "li 





700 







u 24, 





800 





2 animals. 



f July 24, 9.00. Dying. 



\ 11 25, 11 Found dead. 



II 

 II 

 II 



900 

 1000 

 1200 

 1500 







July 26, 9.30 a.m. Found dead. 

 1. 30, 9.00 a.m. Released. 



.1 ,1 Dying. 

 „ 27, 7.30 p.m. Dying. 



II 



1700 







u 26,8.30 a.m. Found dead. 



BARK EXTRACTS. 



Contrary to opinions expressed in some reports upon sawdust pollution, I found 

 that aqueous extracts from bark of white pine, hemlock and cedar were not nearly so 

 poisonous as the sawdust solutions. The tanin or other material dissolved out from 

 hemlock bark was of course poisonous; but, in a general way, the effect of bark solu- 

 tions upon adult fish was to kill them by suffocation. The oxidation processes going 

 on in the bark extracts deprived the water of the oxygen usually dissolved in it, and as 

 a consequence fish immersed in it soon died. That this was the true cause of death was 

 evident from the fact that bark solution when aerated, that is, with air made to bubble 

 through it, supported fish life just as well as any normal water would do. 



BLACK BASS FRY. 



For the successful results obtained in many of my experiments I am indebted to 

 the Department of Marine and Fisheries, Ottawa. On June 27, Mr. Halkett, an officer 

 of the department, brought to me about 100 black bass fry. They had been hatched out 

 in the natural pond at Belleville and were a fine lot of fry, each about an inch long. I 

 placed them in a galvanized-iron tank about 4 feet long, 3 feet wide, the water in it 

 being kept about 3 to 4 inches deep. A copious flow of tap water from Lake Ontario 



