391 
ties is submerged by the flood. It will be noted that the ex- 
ceptions lie at the close of this period, when low water brings 
local factors into prominence. It is at this time also that the 
differences in the amplitude of production are most in evidence. 
1898. 
(Table VII., Pl. XXXIV.) 
Six collections made at the outlet of Flag Lake in this 
year in July-September for the purpose of detecting Trocho- 
sphera are introduced int» !:ble VIL, since they throw some 
additional ight on productio. :e _. The four collections in 
July exhibit a very low level of plankton content, the highest 
being .62 cm.’ per m.*; and the level is not raised in the single 
August collection. However, with the run-off of the slight 
rises of August and September we find a rise to 15.54. At this 
time water of overflow was making its way from across the 
bottoms at the southern end of Thompson’s Lake through the 
marshy swale into the foot of Flag, and thence out to the river. 
The similarity in the movement of production here and 
in other stations is seen in the general low level of production 
in July and the slight rise towards the end of the month. A de- 
cline early in August can also be traced, followed by a rise in 
the next month (cf. Pl. XX XIV., XII. and XXIX.). 
With the exception of the collection on September 6, the 
collections of this year indicate that the effluent of Flag Lake 
is a diluent of channel plankton. This may result from the 
low levels and consequent dominance of the vegetation in the 
lake at this time of low production there. 
SUMMARY. 
The data discussed in the preceding pages lead to the fol- 
lowing conclusions concerning Flag Lake. 
The average production of plankton in this lake, or, more 
properly speaking, marsh (11.46 cm.’ per m.*. or 9.23 on the 
basis of monthly averages), exceeds that in the river (2.19 or 
2.71), This greater fertility appears not only in the averages 
