Studies on Asterionella: I. The Origin and Nature of the Cells Producing Seasonal Maxima

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Abstract
Diverse views have been expressed as to the origin and nature of the cells producing the seasonal maxima in the plankton of certain lakes. Observations on natural populations covering about 5 yrs. are discussed. The effect of varying the physical and chemical conditions under cultural conditions are described. The conclusions are at variance with those of several other workers. Live cells are always present in the plankton of the lakes studied. No morphological resting stages occur. The populations in the inflows, in sheltered areas and on the bottom deposits exert no appreciable effect on the seasonal cycle in the open water. The seasonal changes in numbers are due to changes in the physical and chemical conditions in the immediate environment of the cells in the open water.