467 
nections with and contributions from the remaining backwaters. 
The complications arising from the combination of these vari- 
ous factors in varying degrees and the seasonal shifting of the 
two periods in the several years, render any sweeping general- 
izations impossible. 
The following table gives in parallel columns the monthly 
means of plankton per m.° and of river stages in feet above low- 
water mark. 
PLANKTON PRODUCTION AND RIVER LEVELS. 
January | February March April May June 
“s = : 
ws 
o o | o |e o a) r) a ) a) © oe 
Fe igelee Bsr Selo. | Selig eel 2 | as 
a la a ip nO | A A |e a MO | A 
Io¥lllees cgalhero og] |avcane| fe oS Guero adeno ne |Gonntal tendo (Screens 4.63 74 
YSOSi (tee 3-3 Ol|Sarem| Sencar od Ut lee 22359 bel lGocrce ae epsom 1.88] 30.42 
1896| 10.24] .O1 .83} .02] 9.41 Loz! 7.28 7| 6.58} 1.30] 7.38 72 
TOO il sieterlere 11.13] .04] 13.89] 38] 13.40] 5.11] 9.41] 5.62) 5.54 27 
1898] 5.08) .45} 5.94) .27| 12.99 33| 14.00 OF LUGS xx530|) TH-53| 3.96 
1899} 7.99] .18} 7.02} .81] 13.05 Po OBE | eco MAN COe sees eel itee Gael ome 
Mean| 7-77| .21| 7-29] .23] 12.34 27| 10.02] 4 59| 9.18] 6.08] 6.19] 7.22 
July August Sept. Oct. Nov. | Dec. Ann’l Mean 
; al iRaie 
o a] re 44 o | Oe eat |! OS ia = a v eh 
Ples|e|s8| PES sles) sles) 2 | ss | 2 | es 
a | a some oie | Oe] ® le mo | a a 
2.32 5.12 “1.99 9.67] 4.43] 1.36|2.96] .61/2.97] .10' 3.41 10 | 4.63] 2.53 
3.17] 9.33} 2-43] 4-03] 3.42] 1.52) 1.93] .57/2-20]3.02, 6.16) 1.14] 3.61] 5.91 
4.55] 1.44] 7-42] 1.12] 4.62) .38]/6.04/1.11/ 5.89 02,5 48 -76| 6.98] 1.05 
6.05] 4.69] 2.29] 3.65] 2.01] 8.83] 2.01] 5.95) 2.82) 1.00, 3.22) .56| 6.90) 3.51 
5.70} .58) 3.66] 91] 4.44] .69/ 4.86] .24/7.44) .25] 6.59] 99] 8.02] 2.03 
io doleo.c1250] | Paesal >cooes| | seectel tose ocean Noted Raced poooe fooondel) come) |yeodosl|! of? 
4.36] 4.23} 3.56) 3.88] 3.82) 2.56/3.56/ 1.70) 4.26] .88 4.97 Al eet oBe 2.71 
An inspection of the table shows at once the complexity of 
the problem, and yields the following generalizations. 
In January-February, a period of sustained minimum tem- 
peratures, high levels are attended by a small, and low levels 
by a larger, plankton content, with the exception of stagnation 
conditions in February, 1895. This contrast results from the 
