364 ELEMENTARY BIOLOGY. [CHAr. 



LABORATORY \YORK. 



A. Examine duckweed roots, confervas, &c., with J inch 

 objective avoiding pressure ; having found a group of 

 Vorticdlcc note the following points with a higher 

 power. 



I. 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). 



p. The flattened central disc projecting above 

 the peristome. 



y. The ci/ia fringing the disc. 



S. The depression between the peristome and 

 disc. 



€. The vesiibuliun ; a chamber in the liollow 

 between the peristome and disc. 



c. Structure. 



a. The thin, transparent, homogeneous external 

 layer {eufic/e). 



p. The granular layer (ee/osare) inside the cuticle, 

 longitudinally striate at the base of the bell 

 {myopha7i layer). 



y. The central more fluid part {endosare) not 

 shari:)ly marked off from (i. 



