58 A GUIDE FOR THE STUDY OF ANIMALS 



Suggested drawings. 



a. Hydra undisturbed, and hydra after being touched 

 or shaken. 



b. A hydra in successive poses to show its flexibility. 



c. A hydra taking food. 



d. Hydras to show reproduction in one or both ways. 



e. A section of hydra, showing details. ' ^ 



Comparative Study of Coelenterates 

 Materials. 



Various coelenterates, such as hydroids, hydro-medusae, 

 jellyfishes, sea anemones, corals, sea fans, etc. Since 

 nearly all the coelenterates except hydras are marine forms, 

 these will usually have to be dead specimens, preserved in 

 formalin or alcohol, or put up as permanent preparations 

 for the microscope. 



Definitions. 



Colony, as used in this group, a number of individuals 

 descended by budding from an original one, and remaining 

 connected. 



Polyp, an individual coelenterate ; one of the individuals 

 in a colony. 



Observations. 



1. How large is an individual specimen in the form you 

 are studying.' If the form is colonial, how large is the 

 colony or portion of a colony you are studying } Estimate 

 the number of individuals in it. Is the colony free-swim- 

 ming or attached .' If attached, to what is it usually fastened .' 



2. Compare the individual you are studying with a 

 hydra, as to size and shape of the body, the location of the 

 mouth, and the size, number, and arrangement of the ten- 

 tacles. 



