THE SIMPLER ORGANISMS 105 



with the protococcoid algae, in the latter with the masti- 



gophorous protozoa. 



Euglena is a common flagellate that will serve for intro- 



duction to the group. It abounds in sluggish waters, and if 



a quantity of trash and bottom 

 silt be placed in a large glass jar 

 and allowed to stand awhile, Eu- 



FIG. 6i. Euglena. n, nucleus; glena will usually be found swim- 



m, mouth; cv. contractile . - .- - 



vacuoie with pigment fleck, p, ming in numbers at the surtace 



beside it; fl, flagellum. , . .. . 1-1, -rr 



on the side next the light. If 



abundant it will be very evident by its bright green color. 

 It may form a green film on the surface visible to the 

 unaided eye. 



If a drop from this film be mounted for the microscope 

 and examined one sees as soon as he finds the organisms 

 that they exhibit the bright green chlorophyl color of the 

 algae along with the active swimming movements of very 

 lively protozoans. The swimming is rapid, and at first it 

 may be difficult to keep a single individual in the field of 

 observation. It is jerky, too ; not the regular and orderly 

 progression of a ciliate, but quick movements from side to 

 side, due to the lashing of the long flagellum at the anterior 

 end of the body (see fig. 61). 



In an individual that .has settled to creeping about on the 

 slide one may observe the form of the body oval, blunt in 

 front and pointed at the rear, showing a transparent 

 ectosarc, and an endosarc filled more or less completely with 

 green chlorophyl, and containing near the front end a 

 pigment fleck of more or less orange color. The flag- 

 ellum may be seen to be as long as, or longer than the 

 body. It may be broken off, however, and if present it is 

 so transparent it can only be seen in very favorable light, 

 or sometimes, only after staining. Beside its base is a 

 cleft a rudimentary mouth a receptacle for solid food 



