20 



INVERTEBRATE ANIMALS. 



in many cases into an " ectosarc " and " endosarc." In the endosarc 

 in most ProUrMt is found the solid or hollow body, known as the 

 " nucleus " (iig. 3, A), and this may have a still smaller body, the 

 "nucleolus," attached to its external surface, or embedded in its 

 interior. The "nucleus" and "nucleolus" have often been sup- 

 posed to have a reproductive function ; but there appears to be in- 

 sufficient evidence for this conjecture. 



Fig. S. — A, Amfjtha yirotfiiR, wil.h the pseiTtlopodia protrudcl, enlarged 200 diameters 

 (after Leidy) ; ii, Nucleus; c, Contractile vt-sicle ; v, Ow of tlie larger food-vacu- 

 oles ; en, The graiuihir end<.isarc; ec, The transparent eetosarc; a, A cl'U of an 

 Alga taken in as fund (other cells of the same Alga are obliquely shaded). B, 

 A>i'":li<'- radirtnt, enlarged 500 diameters (af^er Leidy). The body shows two large 

 vacuoles, but no nucleus m- enntractile vesicle. The long and delicate pseudopodia 

 are protruded. 



In one division of the I'mtozo/i (the Iiifii.wria) there is a perma- 

 nent mouth and a short gullet, but in all the others there are no 

 <lcfinite organs connected with the prciccss of digestion. In nci I'ru- 



