GENERAL BIOLOGY 



and observe the extrusion of a clear drop of fluid at the moment 

 of contraction of the contractile vacuole. 



7. Respiration. Place a number of the animals in a drop of 

 phenolpthalein (which loses its rose-color in the presence of 

 carbon dioxide) and note the result; also note the manner in 

 which the animals collect at the surface of a dish in which the 

 water is very foul. What do these observations teach? Are there 

 any organs of respiration? 



II. REPRODUCTION. 



1. Fission. Observe a Paramecium in the process of division. 

 In a stained preparation note what changes take place in the nuc- 

 leus and micronucleus during this process. Can you detect any 

 difference between the two daughter individuals? How do the 

 contractile vacuoles, the buccal grooves and the gullets arise in 

 the two ? Draw three stages in fission to show all of these points. 



2. Conjugation. Study and draw living individuals in the act 

 of conjugation. What portions of the body are in contact? Is there 

 any distinction of size or sex in the two individuals? In stained 

 preparations study the nuclear changes which takes place during 

 conjugation. Draw three specimens to show different stages in 

 the nuclear changes. 



III. IRRITABILITY. 



1. Automaticity. Does the animal appear to act of its own 

 accord or only through the influence of external stimuli? 



2. Movement. How many kinds of movement does the animal 

 exhibit? What are the organs of locomotion? With a dissecting 

 lens observe the movements of an animal in a drop of water. 

 Does it move in straight lines? Does it keep one side uppermost? 

 How does it alter its course? Can it move backwards? By means 

 of lines and arrows plot the movements of an animal during one 

 minute. By means of powdered ink observe the direction of cur- 

 rents over the body. What is the direction of the currents in the 

 buccal groove? 



3. Sensitivity. Is the animal sensitive to touch or pressure? 

 How does it behave when in contact with a solid body? Place a 

 small drop of salt solution colored with Chinese ink on a slide and 

 note whether the animals are sensitive to this substance. In similar 

 manner test them with 1/50 per cent and i/io per cent acetic 



[40] 



