34 ZOOLOGY. 



its body. The Amoeba reproduces its kind by simple di- 

 vision, as seen in Amcela sphmrococcus Haeckel (Fig. 11). 

 This species, unlike others, so far as known, becomes encysted 

 {B), then breaks the cell- wall and becomes free as at A. 

 Self-division then begins as at C, the nucleus doubling it- 

 self, until at Z) as and D b we' have as the result two individ- 

 uals. 



Order 1, Forarainifera.' — Besides Ammha, several other 

 forms, either naked or shelled, produce, by division of an in- 

 ner portion of the body, numbers of ciliated young, as in 

 the naked Pelomyxa, in certain many-chambered Fora- 



minifera, and in CollosphcB- 

 ra. An example may be 

 seen in the European Pelo- 

 myxa palustris Greef (Fig. 

 13). This creature lives in 

 the mud at the bottom of 

 fresh-water pools, and when 

 first seen resembles little 

 dark balls of mud a milli- 

 metre in diameter. Instead 

 of one nucleus, there are 

 numbers of them, and nu- 

 merous contractile vacuoles 



Fig. Vj.— Pelomyxa palustris. A, a, cieai z,,, , -,, a • -i ±^ ti 



cortical portion; 6, diatoms enclosed in the nlled. With a nUld., tOgetlier 

 body-mass. 5, amoeba-lilce bodies orisinatine -li ■ i mr 



from the nuclei, whicli after leaving tlie body With SplCUleS. J ne yOUng 



pass into monad-iike forms, C; n, nucleus; „__ _j. fl„„j. oTvimVio Ii'Vq / 0^ 



c, contractUe vesicle.— After Greef. ^re at Qrst amceba-llke (±1), 



originating as " shining 

 bodies," which have resulted from the self -division of the 

 nuclei. These amoeba-like bodies finally assume an active, 

 monad-like stage C, and move about by means of a cilium 

 or lash. 



We now come to the shelled Amoebse, or genuine For am i- 

 nifera. A common type is Arcella, whicli secretes a one- 

 chambered silicious shell, found in fresh water, and a 

 representative of the monothalamous, or one-chambered, 

 Foraminifera ; while the many-chambered forms are 

 marine, of which Globigerina huUoides (Fig. 13), found 

 floating on the surface of the ocean, with its pseudopodia 



