42 



MARINE AND FISHERIES 



6-7 EDWARD VII., A. 1907 



These determinations indicate clearly enough that the stored material in wood 

 cells comes away in diminishing quantity every time fresh water is added to saw- 

 dlist. 



WHITE PINE. 



A long series of experiments were made with water obtained by soaking 360 

 grams of white pine sawdust in 7000 c.c. of tap water and changing the water at 

 irregular intervals. During a period of three weeks the water was changed twenty 

 times. In 1,000 c.c. of the twentieth solution, there was found to be 80 m.gs. of solid 

 matter dissolved out of the pine cells. During every day almost of the three weeks, 

 the effects of the poisonous water were tested by immersing fish eggs, adKilt perch, 

 aquatic worms, tadpoles, copepods, daphnia, hydra, vorticella and black bass fry in 

 the water, and in every instance death followed sooner or later. Sometimes death 

 took place in a few minutes, sometimes in a few hours, the result depending upon the 

 strength of the solution. When air was made to bubble through the poisoned water, 

 the animal lived somewhat longer. 



CEDAR SAWDUST. 



A similar series of experiments were carried out with cedar sawdust. In this 

 case, 400 grams of sawdust were soaked in 7000 c.c. of tap water. The water was 

 changed 30 times during a period of five weeks, and a 1000 c.c. of the last solution 

 of it — ^were found to contain 155 m.g.s. of solid matter. The water was tested almost 

 daily by immersing animals in it, just as in the case of pine extracts. The cedar water 

 was found to maintain its poisonous character for a longer time than pine. In other 

 words, cedar wood cells contain more poisonous matter than pine wood cells. 



EXTRACTS QUICKLY SOLUBLE. 



The experiments hitherto described would seem to indicate that some considerable 

 time was required for the water to dissolve out the poisonous extracts from white pine 

 sawdust, but such is certainly not the case. This was clearly shown in the following 

 experiment. Fig. 4. Two minnows were confined in a bottle containing 600 c.c. water 

 and eighteen grams of white pine sawdust. Fresh water was made to enter and leave 

 at the rate of 100 c.c. per minute. The inlet tube passed straight to the bottom of the 

 vessel, and its lower end was therefore buried in about an inch of sawdust. One animal 

 lived forty minutes, the other fifty. When the incoming water was reduced to 80 c.c. 

 per minute three minnows lived only from three to five 

 minutes. When the fresh water entered at the rate of 125 c.c. 

 per minute, minnows lived from twenty to ninety minutes. 

 The control animals were kept for a week in a similar bottle,, 

 without sawdust, of course, and with water coming in at the 

 rate of 110 c.c. per minute. In these experiments the poisonous 

 extracts must have been coming away all the time. The 

 moment the bottle was full of water the minnows were slipped 

 into it. Consequently, when the fish were killed in five min- 

 utes, the 600 c.c. at first in the bottle, and 400 c.c. additional 

 water were poisoned. When they were killed in ninety min- 

 utes, no less than 11,250 c.c. were poisoned. That is, the per- 

 centage weight of sawdust to poisoned water was *16 per cent. 

 This determination is important, as we shall see later, when 

 we come to compare it with the percentage of sawdust thrown pig. 4. 



into the Bonnechere river. 



COMPARATIVE RESULTS. 



After obtaining the general results indicated in the preceding part of this paper, it 

 seemed desirable to plan a series of experiments that would show comparative results 



