26 



The ))lace occupied by Ottawa river water in this Ust is certainly 

 one of bad eminence. As this water has been examined at irregular 

 intervals since 1888, I may add the following results : — 



Ottawa River, April, 1890. . . 

 " August, 1890. 



4.886 

 6.387 



It will be seen from these numbers that while the amount of 

 oxidizable organic matter in the river varies from month to month as 

 might be expected, and according to a law which we have not the 

 necessary data to to discover, the amount is at all times very large, and 

 it behoves us to examine the conditions under which a water 

 containing so large a quantity of dissolved organic matter is safe as an 

 article of food. That the organic matter is not pet se of an injurious 

 nature is sufficiently evident from the fact that we and our fathers do use 

 it and have used it with impunity. Let me ask your attention for a few 

 moments to another matter. There is a large class of diseases generally 

 spoken of as zymotic which have this property in common. Whenever 

 a single case of such a disease occurs in a locality we may be pretty 

 sure that mimediately in its vicinity, and gradually further and further 

 from that point as a centre, we shall find the disease spreading until it 



