364 ELEMENTARY BIOLOGY. [CHAP. 



LABORAl'ORY WORK. 



Examine duckweed roots, confervae, &c., with J inch 

 objective avoiding pressure ; having found a group of 

 Vorticellce note the following points with a higher 

 power. 



In the extended state of the animal, 

 a. The body. 



a. Its size (measure). 



b. Form ; broadly speaking, that of an inverted 

 bell : note — 



a. The prominent everted rim {^peristome). 



/?. The flattened central disc projecting above 

 the peristome. 



y. The cilia fringing the disc. 



8. The depression between the peristome and 

 disc. 



€. The vestibulum; a chamber in the hollow 

 between the peristome and disc. 



c. Structure. 



a. The thin, transparent, homogeneous external 



layer {cuticle). 

 y8. The granular layer iectosare) inside the cuticle, 



longitudinally striate at the base of the bell 



{inyophan layer), 

 y. The central more fluid part {endosarc) not 



sharply marked off from f^. 



