425 
greatest in the most differentiated localities, Quiver and Dog- 
fish lakes. It might also have been expected in Flag Lake (PI. 
XXXIV.) if examination had continued there beyond the mid- 
dle of July. It would seem, accordingly, that similarity in the 
course of plankton production in different localities is to a 
large extent a function of the community of environmental 
factors, and possibly also of the similarity of the constituent 
organisms. 
1898. 
(Table IX., Pl. XLII) 
There are 22 collections in this year, at fortnightly inter- 
vals, in March—December. The average production for the year 
is the unsurpassed amount of 44.08 em.’ per m.’, with a maxi- 
mum, also unsurpassed in our records, of 224.48 on Aug. 25. An 
unusually high level of production is also maintained from Aug. 
9 to Dec. 13, averaging 63.54 em.*, and falling below 30 in but 
two instances. 
Water re-entered Phelps Lake with the flood of February, 
river stages passing 8 ft. on the 12th and 10 ft. on the 20th. 
From this latter date until June 28, with the exception of 4 
days in May, levels continued above 10 ft., so that a continued 
current of overflow from the bottom-lands to the north passed 
through the lake to the river. Declining river stages continued 
from June 28, passing 8 ft. July 9, thus permitting a run-off for 
a total of 138 days from the lake to the river in the period of 
spring and summer floods. To this must be added 7 days of de- 
clining levels above 8 ft. in the November-December rise, mak- 
ing a total of 145 days of contributions to channel waters from 
this lake. This is the most extended period of contribution in 
the years of our operations, and is a result of the unusually 
high and prolonged floods which brought the average height of 
the river up to 8.02 ft., almost bank height, for the year. 
The plankton content of Phelps Lake waters in the 10 col- 
lections made during the period of discharge above noted, is in 
excess of that in the channel in 7instances by from 1,4- to 14- fold 
