ABSTRACT
Generally two reproductive modes are considered in Artemia: an oviparous and an ovoviviparous. Morris investigated the relationship between hydration, the onset of metabolism, and the onset of development in encysted Artemia. Some animals indeed produce cysts which emerge without a previous dehydration or any other treatment. Visceral mesoderm develops and differentiates independently from the somatic mesoderm. Elongated mesodermal cells discernible from the somatic mesodermal cells surround the whole alimentary canal. The circular and longitudinal muscles of the esophagus are derived from the preantennal mesoderm; its dilatator originates perhaps partly from the preantennal mesoderm, and partly from the second antenna1 mesoderm. Somatic mesoderm is found in the naupliar as well as in the metanaupliar region. In the naupliar region it forms multilayered arcs; in the metanaupliar region it differentiates by cell division from the proliferation site as broad-paired lateral bands beneath the naupliar embryonic ectoderm.
