METHODS of concentration for helminth eggs, such as centrifuging with sodium chloride or zinc sulphate solutions and looping off the surface, or the Gordon – Whitlock egg-counting technique for nematode eggs in sheep fæces, cannot successfully be used for trematode eggs because these collapse in hypertonic solutions owing to their thin shells. The use of chemicals and even the mere act of centrifuging may damage the eggs and render subsequent culture unsuccessful. Multiple sedimentation of fæcal suspensions is laborious and time-consuming. The apparatus shown in the sketch will wash away the colouring matter and reduce the fæcal debris to less than half with the loss of only very few eggs. The resulting suspension is of a consistency which will greatly facilitate other operations, such as dilution egg-counts and straining through bolting silk.
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LEIPER, J. Continuous Sedimentation for the Concentration of Trematode Eggs in Fæcal Suspensions. Nature 163, 908 (1949). https://doi.org/10.1038/163908a0
Journal of Helminthology (1952)