Use of the basic dyes toluidine blue and alcian blue reveals stacked circular granules, 1 to 3µ in diameter, and a highly vacuolated material within the cells of the proximal segments of the nymphal Malpighian tubules.

It is suggested that cyclical secretory activity occurs, involving coalescence of the granules and vacuolation, to produce a secretion which is liberated into the tubule lumen and then passes into the hindgut.

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