GENERAL BIOLOGY 



than the posterior and bears a long flagellum which may be lost in 

 some specimens. The flagellum arises from the bottom of a pit, the 

 "gullet," or "mouth opening." Observe the contractile vacuole and 

 "reservoir" near the anterior end and the nucleus and the paramy- 

 lum bodies near the center of the body. What color do the paramy- 

 lum bodies take when stained with iodine? Is there any cell sac? 



Look for animals in the encysted condition, showing stages in 

 division. Determine by the use of Schultze's solution whether or 

 not there is cellulose in the cyst. 



Movements are of two kinds: (a) Rapid swimming movements, 

 in which the flagellum is carried forwards, (b) Worm-like move- 

 ments, contractions and expansions by which the anima crawls 

 about. The latter movements are characteristic of Euglena and 

 are called "euglenoid" movements. Draw at intervals to show 

 changes in shape. 



Record the points in which Euglena resembles a plant ; also those 

 in which it resembles an animal. Which do you conclude that it is ? 



Make drawings and notes to show all that you have observed. 



SACCHAROMYCES CEREVISIAE, Yeast. 

 (Division-Thallophyta, Subdivision Fungi, Class- Ascomycetes.) 



Read: Calkins, Biology, pp. 29-34; or 



Parker, Elementary Biology, pp. 71-81 ; or 



Sedgwick and Wilson, General Biology, pp. 184-191 ; 



also 



Woodruff, Foundations of Biology, pp. 213, 310. 



A. MORPHOLOGY. 



Place some growing yeast in a drop of water on a slide and ex- 

 amine under a low power, then under the high one. Observe the 

 small oval bodies or yeast cells. Note: Size; is it constant? Meas- 

 ure several. Shape; does it change? Nature of surface. Mode of 

 union. Is there any regular number or arrangement of cells in 

 the various groups? How many cells in a complete yeast plant? 

 Structure: Observe the cell wall; contents. Is a vacuole present? 

 Where is it found? Do you ever find more than one? Is it con- 

 tractile ? A nucleus is present but it can be demonstrated only by 

 the most careful staining. Place a piece of blotting paper over 

 the cover glass and press firmly upon it ; in this way some of the 

 cells will be bursted and the sac and contents can be studied 

 separately, (a). What is the nature of the sac? Its color? Is the 



[31] 



