Fertilization is effected by the union of two nuclei in all those cases which have been carefully investigated.
Sessiliflora, after fertilization, enlarged.
Many Gastropoda deposit their eggs, after fertilization, enclosed in capsules; others, as Paludina, are viviparous; others, again, as the Zygobranchia, agree with the Lamellibranch Conchifera (the bivalves) in having simple exits for the ova without glandular walls, and therefore discharge their eggs unenclosed in capsules freely into the sea-water; such unencapsuled eggs are merely enclosed each in its own delicate chorion.
The subject of fertilization was one which early excited attention.
Recent Work on the Results of Fertilization in Angiosperms, Ann.