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., Pi. XXXIV.) 



Six collections made at the outlet of Flag Lake in this 

 year in July -September for the purpose of detecting Troe/io- 

 spJuera are introduced into Table VU., since they throw some 

 additional light on production here. 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. PI. XXXIV., 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.l 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 



