THE SIMPLEST MANY-CELLED ANIMALS 



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the result woujd be a tree-like colony with a hydra-like 

 animal at the end of each branch. This, of course, is im- 

 possible for a hydra, for its offspring, formed from buds, always 



FIG. 100. Hydroids. a, colony consisting of root-like base, stem, and a 

 hydranth at end of each branch. 6, piece of a branch with two hy- 

 dranths (hyd) and two medusa buds (med) forming, c, a free medusa. 

 d, swimming larva developed from an egg produced by a medusa, e, f, 

 0, stages in development of a larva into an attached hydroid which by 

 budding will form a colony like that shown in a. (From Parker.) 



separate quickly; but there are near relatives of Hydra 

 which from one individual form a tree-like colony by such 

 repeated budding. These animals are called hydroids, 

 which means hydra-like. The colonies often grow several 

 inches in height, with hundreds of branches and individual 



