1). Digestion. If you have mu;iy favorable specimens, stain 

 with neutral red. in the same way as with 1'aramecia; determine 

 whether an acid is present, and if it disappears before the waste 

 matter is discharged. 



c. Defaccation. This is not easily observed. !);> y>u know 

 how it occurs? 



d. E.vcretion. Contractile vacuole, as in Paramecium. With 

 many favorable examples the external discharge may be observed 

 by the use of India ink, as in Paramecium. 



e. The following questions you may not be able to answer by 

 direct observation, but you should be able to answer them from 

 what you have seen or read: Is there any special method of dis- 

 tributing the food within the body? How does it probably occur? 

 How is oxygen probably taken? Carbon dioxide given oft? Is 

 there any way of producing a current of water, to bring food and 

 oxygen, and carry away waste matter? 



C. HYDRA OR A SEA ANEMONE. 



252. a. Study and describe the taking cf food, by feeding 

 Hydra a small animal or a bit of meat. Keep the specimen in a 

 vessel with a bit of plant, to furnish oxygen, and determine if 

 you can about the length of time taken for digestion. 



1). Does Hydra exercise any choice of food ? Try feeding pieces 

 of plant, or bits of paper. Are they taken ? 



c. After a Hydra has been well fed, will it take more food, or 

 do hungry Hydras act differently from well fed ones in this respect ? 



d. If you have opportunity, observe the egestion of the waste 

 matter. How does it take place? Make a diagram of the alimentary 

 canal in Hydra. Is there any way of distributing the food? Ex- 

 amine the cavity within the tentacles with high power ; .are there 

 any internal currents? 



e. Are there any external currents, for bringing food and oxygen, 

 or carrying away waste matter? 



f. How do respiration and excretion probably occur? Are there 

 any special respiratory or excretory organs? Determine whether 

 oxygen is required, by leaving Hydra in a vessel of boiled water 

 and keeping it tightly closed. Does it live as long as in other 

 water ? 



D. ANNELIDS. 



Study the processes and organs of metabolism, so far as it is 

 possible, in two of the lower annelids, as follows : 



