28 



PROTOZOA 



Profoplosmic 



Jnclusion 



F/oge//um 



Bleph aroplas t 

 Eyespo t 



Reservoir 



Other protozoa and with many of the algae. At times used in 

 elementary courses by botanists, since it furnishes the movement 

 so necessary to intrigue the student, it is unquestionably a plant- 

 animal. Its shape is roughly that of a cigar and it moves through 

 the water by means of a flagellum (Fig. 8). 



The body is covered by a cuticle, the external portion of the 



ectosarc. The endosarc contains 

 the gullet, a reservoir, contractile 

 vacuoles, chromoplasts and a 

 nucleus. 



Some authors have claimed 

 (apparently without observa- 

 tion) that Euglena does not in- 

 gest solid particles. The writer 

 has observed with a class of 

 thirty students a whole culture 

 of Euglena in the act of ingest- 

 ing food granules. The animal 

 thrives best, however, when 

 given abundant sunlight. It is 

 quite evidently one of those 

 Phytozoa which is able to utilize 

 chlorophyll as well as to ingest 

 solids. 



The red " eye-spot " is ap- 

 parently composed of material 

 with the power of absorbing 

 light. Reaction to shadows 

 occurs in Ruglena. just he/ore the 

 pigment spot reaches the shaded 

 region. In Volvox, a colonial 

 flagellate, each cell has a true 

 " eye-spot." Strong light produces negative phototropism. 



Economic Importance of Flagellates. — Uroglena not only colors 

 drinking water yellow, but produces a fishy oily odor similar to that 

 of cod liver oil. Peridinians (Gonyaulax) sometimes turn the sea 

 red as blood off the coasts of California, Australia and India. They 

 remove the free oxvgen from the water and cause suffocation of the 

 fish. Synura tivella produces in drinking water a bitter spicy taste 

 resembling that of ripe cucumbers. Dinobryon, also a colonial form, 



Nucleus 



— Fttramy/on body 



Pyrsnoid 



Fig. 8. Euglena gracilis. (Drawn by H. 

 N. Lammers. After W. B. Baker.) 



