76 American Fisheries Society 



corn before the Chicago Drainage Canal was opened, and 

 which is now under water during the greater part of the 

 breeding season of our Illinois River fishes. In this field 

 Richardson found that about 1,500,000,000 eggs were de- 

 posited on something like 600 acres of area. This number 

 was arri\ ed at by counts of the eggs on carefully selected, 

 measured areas, multiplied by the ratio of the measured sur- 

 faces to the total acreage on which eggs were deposited. 

 Approximately 90 per cent of this billion and a half of eggs 

 were killed by fungus infection in 1910, and so failed to de- 

 velop. In 1911 the water of the river was unusually low, 

 and only about 300 acres of this tract was covered at the 

 breeding season, but the percentage of eggs destroyed by 

 fungus infection was even greater than that of 1910, 

 amounting, by Richardson's counts and estimates, to 98 or 

 99 per cent. It was noticed that where an egg lay in con- 

 tact with a bit of rotting vegetation or other decaying de- 

 bris, it was almost certain to be f ungused ; but where the 

 water was comparatively clear and clean, and the weeds 

 were fresh, practically all the eggs hatched — a point of 

 special importance in view of its bearing on the care and 

 management of both natural and artificial breeding grounds 

 of fishes. The saprolegniaceous fungi which kill the eggs 

 and the young fry of fishes, and sometimes older fishes as 

 well, live primarily upon dead organic matter in the water, 

 and do not require a living host; and they can be conveyed 

 from the dead organic matter in the water to the living 

 eggs or the living fry. 



One result of our season's work was to confirm an 

 opinion which I have had before that the productivity of 

 the principal waters of the state can only lie maintained and 

 developed when the state gets control of certain selected 

 important breeding grounds of the most important species, 

 and takes care of them as it would of any other property: 

 that it will not do to leave these matters to mere chance. 



Another thing of particular interest is the fact that we 

 found main- nests i^\' large-month black bass in the breeding 



