Figure 1. Hatching of the egg of S. japonicum, light microscopy.

A. Activated larva prior to translocation in the shell. The egg on the left hand side contains an activated larva. Here the miracidium lies longitudinally in the egg and its terebratorium is clearly evident. B. The same larva has turned so that it lies across the egg. C. Egg immediately after shell rupture. The outer envelope and vacuoles are swelling and obscure the now smaller shell. D. The outer envelope is now markedly expanded and the miracidium swims actively within its increasingly viscous matrix. The shell lies to the bottom left of the figure, and is slightly out of focus. Abbreviations: OE- outer envelope; Mir- miracidium; S-shell; T-terebratorium.