374 ELEMENTARY BIOLOGY. [CHAP. 



1. Size ; differing considerably in different specimens. 

 Measure. 



2. Outline; irregular, produced into a number of thick 

 rounded eminences (pseudopodia) which are con- 

 stantly undergoing changes : sketch it at intervals of 

 five seconds. 



3. Structure. 



a. Outer hyaline layer (ectosarc), tolerably sharply 

 marked off: inner granular layer (endosarc) be- 

 coming more fluid centrally. 



b. Nucleus; a roundish more solid-looking body, often 

 highly granular. 



c. Look for the paranucleus, a small granular body 

 lying (if present) close to the nucleus, towards 

 which it always remains constant in position. 



d. Contractile vesicle ; (if present) a roundish clear 

 space in the ectosarc which disappears peri- 

 odically, and after a short time reappears; its 

 slow diastole rapid systole. 



e. Ingested foreign bodies; Diatom cases, Des- 

 midice, &c. 



4. Movements. 



a. Watch the process of formation of a pseudopo- 

 dium. A hyaline ectosarcal lobe first appears ; 

 then, as it increases in size, the granular endosarc 

 flows into it. 



b. Locomotion; watch the process, a pseudopodium 

 is thrown out, then the rest of the body is drawn 

 up to it, and the process is repeated. 



c. If the opportunity presents itself, watch the pro- 

 cesses of the ingestion and egestion of solid 

 matters. 



