Abstract
The contractile vacuole of Amoeba verrucosa is formed by the union of a variable number of lesser globules. Subsequent to each contraction a new series of contributary globules may appear in the same location as the preceding vacuole, but this is not invariably the case. Random formation of new vacuoles is common, either at some distance from the original organelle, or close by. The walls of two functioning vacuoles may lie in contact for some time without confluence.
The wall of the vacuole is easily indented with a blunt microneedle. A sharp-pointed microneedle will induce artificial systole by perforation of the wall of the vacuole.
A large vacuole, or a group of contributary globules, freed into the water by ripping open a cell under slight pressure, retain their identity in this medium for some time. A quick upward thrust of a blunt needle against a large vacuole apparently causes its rupture into the surrounding endoplasm, for an increase in fluidity is observed in this area. This would imply the miscibility of vacuolar fluid and endoplasm.
The contractile vacuoles of Paramecium caudatum become dilated on the addition of Grubler's Alizarin blue to the culture. The distended vacuoles together with their feeders become set, gradually taking on a vivid blue color. This stain is specific for the vacuolar walls, and, although it appears long before ciliary action ceases, should be classified as a sub-mortem rather than a vital stain. These stained and distended vacuoles do not collapse when removed from the animal but retain their shape and may be manipulated and dissected with microneedles.
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