III.] THE PEOTEUS ANIMALCULE. 21 



animals, and therefore is, like them, in the long run, depend- 

 ent for its existence upon some form or other of vegetable 

 life. 



LABORATORY WORK. 



Place a drop of water containing Amcebce on a slide, cover 

 with a cover glass, avoiding pressure, and search over with 

 J inch obj. : having found an Amceba, examine with a higher 

 power. 



1. Size: differing considerably in different specimens. 

 Measure. 



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

 rounded eminences (pseudopodia) which are constantly 

 undergoing changes : sketch it at intervals of five 

 seconds. 



3. Structure : 



a. Outer hyaline border (ectosarc), tolerably sharply 

 marked off: granular layer (endosarc) inside this, 

 gradually passing into a more fluid central part. 



h. Nucleus : (absent in some specimens) ; a roundish 

 more solid-looking particle, which does not change 

 its form. 



c. Contractile vesicle : in the ectosarc note a roundish 

 clear space which disappears periodically, and after 

 a time reappears ; its slow diastole— rapid systole. 

 Not present in all specimens. 



d. Foreign ladies (swallowed) ; Diatom cases, Des- 

 midice, &c. 



