1902-3.1 Sawdust and Fish Life. 443 



water drawn off for the eleventh time ; air bubbling through it very 

 rapidly. Moribund in ten minutes. 



Placed in this extract about a dozen worms gathered from the mud 

 in water about three feet deep. These animals were massed together 

 and lying among the roots of aquatic plants. The moment the solution 

 touched them they separated all over the bottom of the watch glass, 

 wriggling in all directions and voiding their faeces. In three hours they 

 were all dead. So were two small phyllapod crustaceans which happened 

 to be along with the worms. 



June 24th. Placed a batch of about fifty aquatic worms in cedar 

 extract drawn off for the twelfth time. At first great wriggling ensues 

 with evacuation of faeces ; then constrictions occur in each segment of 

 the body, making the animal look somewhat like a string of beads ; 

 then the hinder end appears to disintigrate but leaves the front end 

 living and moving ; finally the head dies. In two hours most of them 

 were dead, but in a few the head was still alive. 



June 25th. At 9.15 a.m. placed a tadpole one inch long in cedar 

 extract drawn off for the twelfth time. Apparentty dead in fifteen 

 minutes, but revived in about an hour when returned to fresh water. 



Up to this time all experiments with cedar extract had been con- 

 ducted with what might be considered as saturated solutions ; that is, 

 the solution used was siphoned off from the bottom of the aquarium 

 where the sawdust was lying and where the dark colour showed the 

 extract to be the strongest. From this date the experiment was varied 

 by throwing out all the water, filling up the aquarium with fresh water 

 and allowing the bag of sawdust to float at the top of the water. In 

 this way the solution was uniform in colour and strength throughout the 

 aquarium. The animals were then as a rule placed in the aquarium 

 and usually swam about below the floating sawdust bag. 



June 27th. Mr. Halkett, an officer of the Department of Marine and 

 Fisheries, arrived to-day from Belleville, bringing with him about 100 

 black bass fry. The weight of one of these of medium size was found 

 to be 135 milligrams ; its length one inch. 



Placed two of these fry in cedar extract drawn off fourteen times. 

 Both appeared to be dead in two minutes. Placed in fresh water they 

 did not revive. 



June 28th. Two black bass fry in cedar extract drawn off sixteen 

 times from the same sawdust, died in two hours. 



