335 



while traces of vegetation worth mentioning were found at only two 

 stations in all three lakes all stimnier. The collections of 1922 are thus 

 practically altogether open-lake dredgings, from areas where the bottom 

 animals are subject to the full influence of low oxygen when it occurs, 

 and where they receive a minimum of aid from the reacrating or 

 freshening eiTects of shore vegetation and spring water. Noting the 

 very wide extent to which the largely deaerated waters of the river 

 spread out in the upper lake wide-waters opposite Rome — where the 

 bottom dissolved oxygen was under 1 p. p. m. for fully a half mile to 

 the eastward of the mid-channel line on August 9, 1922 — it has seemed 

 best to emphasize distance from mid-channel rather than depth in the 

 zonal subdivision of the wide waters. Thus in all cross-sections in 

 1932 in the lake proper we had first a mid-channel stop, in an imagi- 

 nary channel some 700 feet wide, the approximate width of the luain 

 channel at ChiUicothe ; next a first wide-water zone embracing several 

 collections in which the first haul was usually taken 400 to 600 feet 

 to either side of the mid-channel line; and last a second wide-water 

 zone extending from 1800 to 4500 feet eastward or westward of the 

 mid-channel line, depending upon the width of the lake in the area 

 crossed. 



A table of distances down stream between stations at which cross- 

 sections were made, follows. 



