trate also. But this whole the most experienced naturalist could not distinguish from a Coralarian Polyp. Among Coral Polyps the individual is, then, an association of parts of different form, of which each is equivalent to a Hydroid Polyp.
A Coral Polyp with twelve tentacles is the sum of a considerable number of Hydroid Polyps—one digester, twelve hunters, and a variable number of reproducers. It is formed by the aid of Hydroid Polyps, as flowers by the aid of leaves; or, better yet, as the composite flower is formed by its florets. It is produced in the same way as the Porpita or the Velella; the formation of a colony, the division of physiological labor, the appearance of polymorphism, and the concentration of the parts so elaborated—such is the succession of phenomena which marks the transformation of Hydroida into Velellæ and Sea-Anemones. The Hydroid Polyps are the raw materials which are brought into the factory, and then fashioned and gathered together to form higher individualities.
While these morphological phenomena are taking place, others are also occurring in a physiological order. At first the associated individuals have nothing in common except nourishment, which all are capable of elaborating, but which passes from one to another so that all are equal partakers. It is just here that consolidation begins, but each polyp still preserves his personality. He has his own will, and does not share his sensations with his neighbors; we can wound or even remove one without disturbing the rest. But, in proportion as the colony becomes more coherent, sensations extend farther and farther around the polyp that experiences them. Soon all the individuals
Fig. 11.—Morphology of Tape-worm. 5, fragment of tape-worm showing the joints; 4, single joint enlarged showing ovary, o, generative pore, a, and canals, b; 3, head of tape-worm.
are conscious of that which happens to any one of them, thus forming a colonial consciousness above that of the individual, and finally a single will bends all the special wills to its bidding. A new individ-
