THE BEHAVIOR OF PROTOZOA 81 
the object. Then there are righting movements which are 
brought into play when Loxophyllum is turned over on 
its left side. There is not, as we might be led to expect, 
but a single stereotyped method of righting. The organism 
rights itself by a number of very different methods which 
present an indefinite number of modifications. One cannot 
but wonder when watching the varied movements of this 
eraceful and supple infusorian that a single cell is capable 
of such behavior. 
One of the most highly developed 
types of behavior which has been 
carefully studied in the protozoa is 
exhibited by the large infusorian 
Stentor. There are several species 
of this genus, but all are trumpet- 
shaped, with a mouth situated at 
the bottom of a depression at one 
side of the anterior end. The oral 
end of the organism is surrounded 
by a zone of membranelle which at 
one end descends in a spiral course 
toward the mouth. The whole sur- 
face of the body is covered by uni- 
form cilia, with the exception of a 
small area of naked protoplasm at 
the small end or foot, by means of 
which Stentor is able to attach itself 

to foreign objects. When free in the — Fia. 11.—Stentor_ poly- 
water Stentor is able to swim by yd pan ame cng 
the action of its cilia and membranelle. Like Paramoe- 
cium it follows a spiral course and when stimulated it may 
perform the motor reflex, backing off by reversing the 
beat of its cilia, turning to the aboral side and then going 
6 
