17 



HYDROZOA 



6. A single polyp of Tubularia (Gymnoblastic Hydroid) removed from the colony and examined 

 with a simple lens. 



Circumoral tentacles ; gonophores, on branched processes of the body wall ; large tentacles ; small 

 globular swelling at the base of the body passing into ccenosarc. 



7. Longitudinal section through a polyp of Tubularia. (Low and high powers.) Mouth ; 

 ectoderm ; endoderm of enteron ; en. tent, solid axis of the tentacle, consisting of modified, much 

 vacuolated endoderm cells ; nematocysts ; circumoral tentacles ; gonophores and stalk of gonophores ; 

 oral tentacles ; globular swelling ; ccenosarc. 



