30 FRESH-WATER RHIZOPODS OF NORTH AMERICA. 



and Euglypha, representatives of the Lobose and Filose Protoplasts, the 

 endosarc becomes resolved into nucleated cells, which are of the nature of 

 ova, while the nucleus is resolved into granuliferous non-nucleated cells, 

 finally breaking up into their constituent granules, which are of the nature 

 of spermatozoids. 



AMCEBA. 



Greek, amoibos, changing. 



Tolvox: Linnfeus, 17(30. Chaos: Linnaeus, 17G7. Proteus: Miiller, 1766. Vibrio: Gmelin, 1788. Amiba: 

 Bory, 18-24. Amoeba: Ehrenberg, 1831. 



Animal, when at rest, a spherical or oval mass of soft, hyaline, color- 

 less, homogeneous, pale granular protoplasm, possessing extensile and con- 

 tractile power, and in the active condition devoid of an investing membrane, 

 or any kind of covering. In motion, mostly of exceedingly variable and 

 ever-changing form, and with no absolute distinction of parts, though fre- 

 quently exhibiting more or less disposition to differentiation into an anterior 

 and a posterior region. Ectosarc hyaline, crystal-clear, but, with high mag- 

 nifying power, exhibiting more or less of an infinitely fine granular consti- 

 tution. Endosarc continuous with the former, finely and coarsely granular, 

 mingled with corpuscles of intrinsic and varied character, together with 

 various ingesta, consisting of food, water-drops, sand, etc. Containing also 

 a nucleus and a contractile or pulsating vesicle, or sometimes more than one 

 of either or both of these constituents. 



Body with no external appendages of a fixed or permanent character. 

 Pseudopods digitate, simple or branching, cylindroid and blunt, or more or 

 less tapering- and pointed, or short and broadly lobate, consisting of exten- 

 sions of the ectosarc with variable proportions of the endosarc, or of the 

 former alone. 



Animal in the quiescent state, purged of food and other ingested mat- 

 ters, globular in form, and invested with a structureless membrane, appa- 

 rently produced by coagulation of a portion of the ectosarc. 



AMCEBA PROTEUS. 



Plates I, figs. 1-8; II, figs. 1-13; IV, figs. 22-25; VII, figs. 13-19; VIII, figs. 17-30. 



Dcr Jcleine Proteus. Rosel: Iusecten Belustigung, 1755, iii, 621, tab. ci. 



Voieox Chaos. Linmeus: Syatema Naturae, ed. x, 17C0, i, 821. 



Vol fox Proteus. Pallas: Eloncbus Zoophytorum, 1766, 417. 



Chaos Prothcus. Limueus: Systema Natura), ed. 12 et 13, 1767, i, 1326. 



Volvox Spheerula. Miiller: Verm. Terres. Fluviat. 1773, 31. 



