3528 



THE LOWEST ANIMALS 



groups, the shell-less (Nuda), and the shelled forms (Testacea). The common 

 amoeba, previously described, belongs to the former group, as also does Pelomyxa, 

 a large species found in the form of little white ovoid masses, about the size of 

 a pin's head, creeping on the mud of stagnant ponds; in this animal there is a 

 definite fore part and hind part, the broader end of the ovoid mass being in front. 



ORANGE-COi/DRED PROTOMYXA (magnified 140 diameters). 



The figure represents the capsuled animalcule {Arcella}, common in pools, especially 

 where there is bog moss. The brown horny shell is marked with a finely faceted 

 pattern, and is shaped like a dome with a flat floor; in the centre of the floor is a 

 circular hole, through which short lobose pseudopods emerge from the body in the 

 interior of the dome-like box. Arcella is capable of secreting vesicles of 



air in its body substance, whereby it 

 is enabled to rise. In Euglypha the 

 shell is sac shaped, with a jagged free 

 margin, and the surface covered with regular 

 overlapping scales. In Difflugia the shell 

 is strengthened by the addition of foreign 

 particles. Amoebas are cosmopolitan; 

 occurring in sea and in fresh water, and a 

 few living in mosses or damp earth. Certain 

 forms of dysentery are said to be due to 

 amcebas, or at least to amceba-like phases 

 in the life history of other Protozoa. 



The fungus animals (Mycetozoa) are 



YOUNG CAPSULED ANIMALCULE, SEEN 



FROM ABOVE (magnified). 



a. Fragment of Shell (magnified 600 diameters), claimed both b}' botanists and zoologists. 



