RHIZOPODS. 



553 



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. The figure represents the capsuled animalcule (Arcella), common 

 in pools, especially where there is bog-moss. The brown horny shell is marked 



orange-coloured protomtxa (magnified 110 diameters). 



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 



amoebas, or at least to amoeba-like phases 



in the life-history of other Protozoa. 



The fungus- animals (Mycetozoa), are 

 claimed both by botanists and zoologists. 

 The best known species is the flowers of tan, found in tan-yards, in the form of 

 large creeping masses of naked protoplasm, known as plasmodia. Cakes of proto- 

 plasm become segregated from the main mass, and break up into amceba-like spores, 

 which again fuse to form plasmodia. 



YOUNG capsuled animalcule, sekn fbom above 

 (magnified). ". Fragment of Shell (magnified 



600 diameters). 



