24 



ZOOLOGY. 



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

 vision, as seen in Amceha sphcerococcus Haeckel (Fig. 11). 

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

 (E], 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 D a and D Z> we have as the result two individ- 

 uals. 



Order 1. Foraminifera. Besides Amoeba, 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 Collospha- 

 ra. An example may be 

 seen in the European Pelo- 

 myxa palustris Greef (Fig. 

 12). 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. 12. Pdomyxa palustris. A, a, clear ,, -. -.1 n j i i\ 



cortical portion; ft, diatoms enclosed in the failed With a IlUia, together 



body-mass, li, ;imneb.-i-hkt' bodies originating -LI i,,, rnr.^ TT/-H-I r* 



from the nuclei, which after leaving tlie body With SplCtllCS. J he young 



pass into monad-like forms, (! ; n, nucleus; p q j. fl rt ,j. omrpbl-likp I ft\ 



c, contractile vesicle. -After Greef. tlre at I . \ '' 



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 Amoebae, or genuine Forami- 

 nifera. A common type is Arcella, which 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 Globic/erina bulloide* (Fig. 13), found 

 floating on the surface of the ocean, with its pseudopodia 



X:Qj--c 



