452 



Transactions of the Canadian Institute. 



[Vol. VIL 



ally filled with sawdust. Wood extracts would form, and being cooler 

 and heavier than the clear water, would lie at the bottom of the pool. 

 Of course, fish already in the pool would be driven away, but those 

 coming up or down stream through shallow stretches, and trying to hide 

 in the deeper waters of the pool, might be suffocated or poisoned. 



Comparative Results. 



After obtaining the general results detailed in the preceding part of 

 this paper, it seemed desirable to plan a series of experiments that 

 would show comparative results at a glance. With this end in view, 

 two grams each of different kinds of sawdust were placed in shallow 

 circular dishes containing respectively, 300, 400, 500, 600, 700, 800, 

 900, 1,000, 1,200, 1,500, and 1,700 c.c. of fresh water. After soaking 

 for about five hours in each case, a minnow was placed in each of the 

 dishes. The length of time each animal lived was carefully noted, ex- 

 cept in those cases where death occurred during the night. The results 

 are given in the following tables : — 



White Pine Sawdust. 



Ontario Red Pine. 



