22 STUDIES OF ANIMAL LIFE. 



D. Drawings. 



1. The eiitii-e colony. 



2. A fragment of a colony enlarged to illustrate A 2. 



3. A single hydranth enlarged still more. 



4. A single gonangium enlarged. 



E. Suggestive Questions. 



1. Of what advantage to these animals is this plant-like 



manner of life ? 



2. How would the Hydra need to be modified to carry 



out the hydroid plan ? 



3. A TUBULARIAN HYDROID. 



(See note under Campanularian Hydroid.) 

 . The Hydroid Colony. 



1. Examine an entire hydroid colony with reference to 



its general appearance, and fragments of a colony 

 mounted on slides for details, using 1., l.p., or h.p., 

 as necessary. 



2. Parts to identify : — 



a. The branching stem. 



h. The tassel-like structures (hydranths) at the tips 



of the branches. 

 c. Ovoid structures (medusa-buds) attached to the 



hydranths. 



I. A Single Hydranth. (Corresponding to a single 

 Hydra.) 



1. Are the tentacles arranged as in the Hydra? 



2. Are all the tentacles of the same kind ? 



3. Exactly where are the nettle cells on the tentacles ? 



