23 



HYDRA 



i. A view under hand lens of whole animal in watch glass: body; tentacles; foot; testes if present; ovary 

 if present; bud if present. 



2. The same under low power, placing the watch glass on a slide to prevent rocking: oral cone; mouth; 

 tentacles. _ -di 



3. Mount the animal alive on a slide, taking care that the coverslip does not press too heavily by placing 

 two slips of thin paper under it, and examine it first with a low power, then with a high. Draw portion of 

 tentacle under high power : ectoderm ; thread-cells arranged in batteries ; cnidocils ; endoderm seen through the 

 ectoderm. 



