46 PRELIMINARY STUDIES. 



organism is Euglend viridis. The body is several times 

 as long as wide, and tapers towards both ends. By pecul- 

 iar contractions the organism executes movements which 

 are so peculiarly characteristic that they are known as 

 Euglenoid movements. Besides these motions, Euglense 

 make active, darting movements from place to place. 



1. Hunt for forms that are executing the Euglenoid 

 movements. Study the changes of form, and draw Eug- 

 lenye in three or four typical positions. 



2. Study Euglense in active motion. How is the 

 motion produced ? Look for a flagellum, a very fine 

 thread, at one end, and recall what was said about the 

 motile forms of Protococcus. The beginner will find 

 difficulty in seeing the flagellum. If it cannot be seen 

 in the living organism, run iodine solution under the 

 cover glass, and watch the Euglente as they die. Is the 

 flagellum on the anterior or posterior end ? 



3. Examine a fresh mount of living Euglense for 

 chlorophyl. In what portion of the organism do you 

 find it ? Is it found in one or several Morophyl bodies ? 



4. Near the anterior end notice a small, red spot. This 

 is known as the eye spot, but there is no reason for sup- 

 posing it to be an organ of sight. 



5. Try to find encysted forms, i.e., forms that have 

 surrounded themselves with a thickened wall. The cell 

 wall is cellulose. 



6. Observations that are too difficult for the beginner 

 show that the flagellum grows from the bottom of a hol- 

 low which communicates by a minute passage with the 

 interior of the organism. The lashing of the flagellum 

 causes currents of water to carry particles of solid matter 

 into the organism, where, it is believed, they are digested. 



7. The possession of a cellulose wall in the encysted 

 condition, and the occurrence of chlorophyl would place 

 Euglena among plants ; the Euglenoid movements and 



