24 



HYDRA 



4. Irrigate the animal with 5 per cent, solution of common salt and watch the protrusion of the filaments 

 of the nematocysts. Sketch detached nematocyst with the cnidoblast adhering to it. 



5. Transverse section of the body ; draw with low power, fill in details of small portion with high : ectoderm ; 

 myo-epithelial cells ; interstitial cells ; nematocysts ; basement membrane ; endoderm ; vacuoles ; chloroplasts if 

 present; digestive cavity. 



6. Longitudinal section of the body : parts as in 5. 



