for nauplii in July and August of 1929. The points of late July and 

 early August were determined by the average of a few stations (3 and 

 h respectively) . 



.i/hether the rapid change in abundance indicated was real or 

 the results of inadequate sampling is open to question. The rapid 

 change itself is not \anquestionable evidence of inadequacy, for such 

 changes in abundance are known to occur among the plankton Crustacea. 

 Too much importance should not be given to the fact that few stations 

 were visited, because other periods represented by few stations 

 yielded consistent results. For example, in July of 1930 each period 

 was represented by only three stations, and yet the results for that 

 month fit in well with the results taken before and after. 



Additional evidence of adequacy is found in the close agree- 

 ment in the numbers and times of abundance of Daphnia in the two years. 

 It is extremely doubtful whether such close agreement is merely a 

 coincidence. It is much more reasonable to suppose that the similarity 

 in the curves resulted from a real similarlity in abundance and 

 seasonal distribution. 



The curves for Cyclops were quite different in the two years, 

 and it seems highly probable that the difference was real. If the 

 difference were the result of inadequate sampling, we should expect 

 the ciirves to cross and re-cross in a fortuitous fashion. Actually 

 the curve for 1929 is consistently low and does not cross the curve 

 for 1930 at any point. A similar real difference is indicated by the 

 results for Diaptomus. 



In conclusion it may be said that the consistency and 

 "reasonable" character of the results obtained leaves little doubt of 

 their adequacy for the problem in hand. That is, it seems improbable 

 that the conclusions reached in this paper would have been changed 

 materially if a larger number of samples had been taken. 



Abundance of zooplankton compared with that of other lakes 



It is evident from the discussions of seasonal distribution that 

 successive years may be quite different with regard to the abundance of 

 Crustacea and their times of development. The differences found in the 

 three seasons studied emphasize the need in plankton investigations of 

 continuous observations over several years. In Western Lake Erie there 

 is a need especially for data on the zooplankton between the months of 

 October and April. However, the available data make it possible to 



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