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THE POPULAR SCIENCE MONTHLY. 



trate also. But this whole the most experienced naturalist could not 

 distinguish fi-om a Coralarian Polyp. Among Coral Polyps the indi- 

 vidual 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 vari- 

 able number of reproducers. It is formed by the aid of Hydroid Po- 

 lyps, 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 concen- 

 tration of the parts so elaborated — such is the succession of phenome- 

 na which marks the transformation of Hydroida into VelellaB 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 indi- 

 viduals 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, generatire pore, a, and canals, b ; 3, head of tape-worm. 



are conscious of that which happens to any one of them, thus form- 

 ing a colonial consciousness above that of the individual, and finally a 

 single will bends all the special wills to its bidding. A new individ- 



