Sponges larvae are extremely tender organisms of almost microscopic size (Fig. 4), with the help of her Ciliature lively swimming around, similar small and tender cilium larvae (so called Planula) do have most of the Coelenterata (Fig own. 5), Strobila (Fig. 1). larvas jellyfish (Fig. 7) Hydroids (Fig. 9) larva of Aeginopsis (Fig. 2) larva stadia of some Siphonophora (Fig. 12), flatworms, Turbellaria worms, Müller s larva (Fig. 3), Nemertines own helmet-like formed Pilidium-larva (Fig. 6), Trochophora larvae of the Annelida are distinguished by the possession of eyelash struggle (Fig. 8 and 11) seem quite high organised already and own except with oral canal and alimentary tract provided anus (Fig. 8) still Organs of touch, eyes, old kidneys etc., larvae of the Annelids worms (Fig. 10), development, Ontogenese or Ontogenie, individual history of the development, development of the single living being of the fertilised ovum to the adult living being,
