When the embryo is fully formed within the shell it Ruptures this and gains its freedom.
"Special Report on Diseases of Cattle"
U.S. Department of Agriculture J.R. Mohler
They swam low, and it was very easily seen they had formed part of the coast there, though, as the form of the ice that way was not familiar to me, and as, moreover, the glare rendered the prospect very deceptive, I could not distinguish where the Ruptures were.
"The Frozen Pirate"
W. Clark Russell
Variations also occur in the way in which the volva Ruptures, as well as in the surface characters of the stem, and thus it is often a difficult matter to determine whether all these forms represent a single variable species or whether there are several species, and if so, what are the limits of these species.
"Studies of American Fungi. Mushrooms, Edible, Poisonous, etc."
George Francis Atkinson