IX.] THE BELL- ANIMALCULE. 91 



0. The granular layer {corticallayer) inside the 



cuticle. 



[Its fine transverse striation.J 

 7. The central more fluid part, not shai-ply marked 



off from /3. 



The various clear spaces {alimentary vacuoles) 



in it, containing foreign (swallowed) bodies 



(Diatoms, Protococcus, &c.). 

 S. The contractile vesicle; its position, in the 



cortical layer just beneath the disc; its systole 



and diastole. 



€. The nucleus; an elongated curved body in the 

 cortical layer; sometimes nearly homogeneous, 

 sometimes more distinctly granular. The nu- 

 cleus is usually indistinguishable until after 

 treatment with iodine (4). 



f. The gullet; sometimes seen in optical trans- 

 verse section as a clear round space; some- 

 times seen sidewise as a canal opening above 

 on the disc, and ending abruptly below in the 

 body-substance.' 



b. The stalk. 



a. Its length and diameter (measure). 



y8. Its structure ; the external homogeneous layer 

 (sheath) continuous with the cuticle ; the highly 

 refractive centre (axis) generally surrounded 

 with granules, and continuous with the cortical 

 layer of the bell. 



2. In the retracted state, 

 a. The body. 



a. Its form ; pear-shaped ; rounded off above ; no 

 disc or peristome visible. 



